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Oil versus Fuel consumption

15K views 80 replies 19 participants last post by  revrnd 
#1 · (Edited)
Chart to estimate oil consumption.

Function f(x) = 9.61307 * 1.0959 ^ MPG

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There is simpler chart that I have devised with rounded numbers to make it easier to remember. I explained it well in the link below which is essentially a guide and not something written in stone.

There are two keys to this guide. The first is the chart that respects the chance in oil demand at different rpm and load. The second is the simple method to calculate a percentage less or more oil using the mpq (Miles Per Quart of oil). So if you prefer 20% less oil, then it is a simple % calculation based on mpq which respects the need for oil at different rpm and load. I firmly believe this is a leap forward.

The hidden advantage is if a tech or the owner makes a change to the oil consumption either purposely or inadvertently, then this change becomes easy to calculate. The same holds if an engine is rebuilt or a change in track or clutching, or anything that affects the fuel consumption. As long as you know the Fuel vs Oil consumption before the change, then you have the ability to compare the before and after.

I keep thinking that I need to submit this to BRP. I know they have their own chart which is essentially what I was able to extract. But the ease in calculating the % increase or decrease may be something new.

Oil vs Fuel consumption (see post 284 that this links to)

Calculating change in oil consumption

Example A:

Sled @ 11 mpg consumes too much oil @ 70 mpq for an average ratio of 25:1
Target decrease @ 85 mpq for a ratio of 31:1

Convert mpq to quarts per 100 miles

100 / 70 mpq = 1.429 quarts
100 / 85 mpq = 1.176 quarts

Calculate percentage
( (1.176 / 1.429) - 1) x -100 = 17.7% decrease in oil consumption

An increase from 70 mpq to 85 mpq = 21% increase in distance
( (85 mpq / 70 mpq) - 1) x 100 = 21.4%

Example B:
Sled @ 16 mpg consumes too little oil @ 225 mpq for a ratio of 56:1
Target increase @ 170 mpq for a ratio of 42:1

Convert mpq to quarts per 100 miles

100 / 225 mpq = 0.444 quarts
100 / 170 mpq = 0.588 quarts

Calculate percentage
( (0.444 / 0.588) - 1) x -100 = 24.5% increase in oil consumption

A decrease from 225 mpq to 170 mpq = 32% decrease in distance
( (225 mpq / 170 mpq) - 1) x 100 = 32.4%

Simpler chart

4 mpg @ 14:1 @ 14 mpq
5 mpg @ 15:1 @ 19 mpq
6 mpg @ 17:1 @ 25 mpq
7 mpg @ 18:1 @ 32 mpq
8 mpg @ 20:1 @ 40 mpq
9 mpg @ 22:1 @ 49 mpq
10 mpg @ 24:1 @ 60 mpq
11 mpg @ 26:1 @ 70 mpq
12 mpg @ 29:1 @ 85 mpq
13 mpg @ 32:1 @ 105 mpq
14 mpg @ 35:1 @ 120 mpq
15 mpg @ 38:1 @ 140 mpq
16 mpg @ 42:1 @ 170 mpq
17 mpg @ 46:1 @ 195 mpq
18 mpg @ 50:1 @ 225 mpq
19 mpg @ 55:1 @ 260 mpq
20 mpg @ 60:1 @ 300 mpq


Example C:

This is the latest chart I put together on Feb 21st, 2022 for a 2018 600 Carb.

The range starts with Longevity for the engine with the oil consumption taken from the E-TEC. The Economy provides roughly 20% greater distance for a quart of oil which figures about 17% savings.

The cool part is mixing 200:1 in the gas raises the oil consumption from Economy to Longevity with the benefit of running mix through the carbs and reeds. Who doesn't want a little more lube to help prevent the carb slides from wearing and causing a high idle? With a 100:1 mix, then the oil injection can be lowered even further for a total of 40% greater distance and still have the same oil consumption for Longevity.

Note how the Economy numbers are the same as Longevity shifted up one line. It makes for an easy chart to remember and use.

The mpq and ratio numbers have been rounded for ease of use, There is no need for being ultra accurate, but rather in the ball park.

Range for Longevity and Economy

12 mpg @ 85 - 100 mpq (~28:1 to ~34:1)
13 mpg @ 100 - 120 mpq (~30:1 to ~37:1)
14 mpg @ 120 - 140 mpq (~34:1 to ~41:1)
15 mpg @ 140 - 170 mpq (~38:1 to ~45:1)

Economy + 200:1 mix = Longevity


Below are several topic links on the subject. Take note of at least the first and last one.

A debate on oil to gas mixture
Trailrider with the 800 SDI in Post #24
Trailrider with 6,600 miles over 212 running hours since last rebuild
Ratios from the Ski-Doo Race Manuals in Post #7
Will too much oil cause a lean failure?
Trailrider's example from a big wood processing timber operation
 
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1
#2 ·
okay, granted, I have 1/4 bottle of whiskey in me right now, but I'm struggling to understand this...

I've never really let my oil reservoir drop below half, but I usually get about 3 tanks of gas per half of a gallon of oil.

6 tanks = 60 gallons

60 gallons = 1000+ miles. So 1 gallon of oil per 1000+ miles.
 
#3 · (Edited by Moderator)
A gallon per 1000??? Wow.

My '18 would burn through a gallon in 300 miles, sometimes even a touch less than that. I had the low oil light pop on at 185 miles one day. That one was thirsty.

My '19 is a bunch better but still uses a gallon in about 450-500 miles.

Then again the '19 was better on fuel too so I'm thinking Daag is on to something here.

Gotta admit, I often shake my head when I read of people getting 18-20 MPG out of an 850. Obviously their riding style is different than mine.

I'm betting my '21 will use virtually no oil, regardless of how much gas it uses. ;)
 
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#5 ·
My buddy was horrified by the oil consumption of his 850 XRS and after owning a dozen Etecs he knew it was different. Called Ski Doo to see what was going on and they said the 850 is set to run approx 20:1. What in the ever loving dogfart is that all about? I have a V6 2 stroke outboard engine, a Mercury made in 2006 that runs at 100:1! Clean burning Etec??? What a load of horsesheet.

What I am saying is there is certainly no set rule of thumb. The earlier 600 etecs SEEM to burn more like 100:1 and the newer 850's obviously 20:1 (by Ski Doos own admission). So while I commend the work you put into writing this up, I am not sure how valuable it is on a wide scale across different brands or engine platforms.
 
#6 ·
Still in its infancy even after near a decade, this is the latest I have come up with. It would be fantastic to have the OEM show something absolute, but if I wait for this it will never happen. So please use at your own discretion and only as a rough estimate.

Given the function f(x) = 9.61307 * 1.0959 ^ MPG, this is mostly for the accuracy of the Direct Oil Injection mapping on the E-TEC, and unassumingly for the Arctic Cat and Polaris equipped with a similar electronically controlled oil pump.

For sleds with a mechanically operated oil pump such as a Carbs and SDI, look for your own range of fuel consumption to estimate the need for oil. Always look for a ball park figure.

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Oil Consumption - Markup.jpg
You lost me at rough estimate and ball park.

Don~
 
#8 · (Edited by Moderator)
I had a 07 Pol 600 efi that got 400 miles to a quart. Did the Gaspe one year, 1500 miles, 1 gal of oil. Sold it running strong with 8000 miles. Came with a 5 year dealer warranty so I was never worried about burning down, never saw another one so good on oil. My new skidoo is even better, uses NO oil at all.
That is excellent fuel consumption. 19.7 mpg (US) is a from BRP for a sample trail ride on the 850. From the chart it is close to 300 miles per quart of oil. Using the function it figures at 287 mpq. By increasing the distance covered for the same quart of oil to ~40% (39% to be precise), it gives 400 miles per quart!

Was the 07 600 a Liberty 4-Injector like the 700? If so it had fuel injectors in the crankcase which made a big difference.
 
#9 · (Edited by Moderator)
A gallon per 1000??? Wow.

My '18 would burn through a gallon in 300 miles, sometimes even a touch less than that. I had the low oil light pop on at 185 miles one day. That one was thirsty.

My '19 is a bunch better but still uses a gallon in about 450-500 miles.

Then again the '19 was better on fuel too so I'm thinking Daag is on to something here.

Gotta admit, I often shake my head when I read of people getting 18-20 MPG out of an 850. Obviously their riding style is different than mine.

I'm betting my '21 will use virtually no oil, regardless of how much gas it uses. ;)
11 mpg @ 75 miles per quart of oil was a remarkable amount of oil for a trail sled. Thanks to your 2018 it provided the missing coordinate to bridge the gap with off-trail.
 
#10 · (Edited by Moderator)
[.....]

I've never really let my oil reservoir drop below half, but I usually get about 3 tanks of gas per half of a gallon of oil.

6 tanks = 60 gallons

60 gallons = 1000+ miles. So 1 gallon of oil per 1000+ miles.
1000 miles to a gallon of oil was roughly 250 miles per quart of oil, so somewhere in between 18 and 19 mpg. Say 18.5 mpg @ 1000 miles, that figures 54 gallons of fuel. Divide by 6 fuel-ups = 9 gallons out of a 10.6 gallon fuel tank on the XP or XS. This is emptying the gas tank more than I am comfortable with, but still reasonable at 85% (9 gallon / 10.6 gallon fuel tank).
 
#11 · (Edited by Moderator)
My buddy was horrified by the oil consumption of his 850 XRS and after owning a dozen Etecs he knew it was different. Called Ski Doo to see what was going on and they said the 850 is set to run approx 20:1. What in the ever loving dogfart is that all about? I have a V6 2 stroke outboard engine, a Mercury made in 2006 that runs at 100:1! Clean burning Etec??? What a load of horsesheet.

What I am saying is there is certainly no set rule of thumb. The earlier 600 etecs SEEM to burn more like 100:1 and the newer 850's obviously 20:1 (by Ski Doos own admission). So while I commend the work you put into writing this up, I am not sure how valuable it is on a wide scale across different brands or engine platforms.
Unfortunately the productions 850 wasn't given the target oil reduction. BRP started their own thread on DooTalk explained they had to keep using the oil consumption from the 800R E-TEC.
 
#12 · (Edited)
The following is an Two Stroke Oil Migration paper from Maxima racing oils.

The JPG file won't come clear due to DooTalk picture compression from a laptop, so I added a PDF version. There was a link to the source that I have removed since it has since become a dead link, but there are copies floating around the internet that can be found by searching Oil Migration Sheet - Maxima. The results shows the oil consumption depends on engine speed and load. The oil vs fuel consumption will be at its lowest at idle, and at its highest under full load.

Miles per Quart is useful to quickly gauge the oil consumption at fuel stops. By graduating the oil tank with a felt type Sharpie for each quarter of a quart, it becomes simpler and faster.

I ride over 2 hours between stops, so I need to at least glance at the oil tank to determine it is in the ball park and not running out of oil. Assuming that most riders will consume anywhere in between 100 to 200 mpq, the oil may need to be checked once or twice a day.
 

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#13 ·
I didn't mention my machine. 2015 600 Etec - Renegade BC.

First 2000 miles I kept track of gas and oil consumption. Trips to steep and deep I was getting around 17 MPG. Trips to the cabin (trails and some off-trail) I would get around 19 MPG.

First year I had the machine, I bought 1 gallon of oil and went 1024 miles. I did neglect to remember that it came with about 1/2 tank of oil when purchased (cheap bostards, LOL)
 
#14 ·
I didn't mention my machine. 2015 600 Etec - Renegade BC.

First 2000 miles I kept track of gas and oil consumption. Trips to steep and deep I was getting around 17 MPG. Trips to the cabin (trails and some off-trail) I would get around 19 MPG.

First year I had the machine, I bought 1 gallon of oil and went 1024 miles. I did neglect to remember that it came with about 1/2 tank of oil when purchased (cheap bostards, LOL)
Half a tank? That is cheap. I wonder if they used the XPS blend lol

So without knowing what sled/engine that you were riding, the actual fuel consumption in mpg could be estimated from the oil consumption. Not bad for a simple chart.

It is a lot simpler than most things we get involved with in our careers and our homes. For a comparison, I would consider how you worked out a problem with the water well to be far more complicated. In hindsight I believe the reason we have trouble understanding something simple as oil consumption is because we never paid enough attention to the subject.
 
#16 ·
Half a tank? That is cheap. I wonder if they used the XPS blend lol

So without knowing what sled/engine that you were riding, the actual fuel consumption in mpg could be estimated from the oil consumption. Not bad for a simple chart.

It is a lot simpler than most things we get involved with in our careers and our homes. For a comparison, I would consider how you worked out a problem with the water well to be far more complicated. In hindsight I believe the reason we have trouble understanding something simple as oil consumption is because we never paid enough attention to the subject.
Pretty sure its mostly that no one really gives a crap about any of this... just a thought.
 
#17 ·
1.5 : 1 Fuel to Oil Ratio

I figured that I was doing something wrong and I realized that IcutMetl was spot on. To paraphrase, too much explanation for too little return.

So this morning I got up early to test a theory that two stroke oil was combustible. I knew that a four stroke push mower would run on 4:1, so I figured why not try 3:1 . After running it 30 seconds with no visible smoke and no noticeable power loss (remember that a push mower has a governor), I figured that this was too easy. So I poured another 40ml of XPS Mineral straight into the tank for a 1.5 fuel to oil ratio. After running the mower for 2 min it was working ok, but a little sputter. I stopped the mower wondering if I should try more oil? I shook my head and thought I better see if it starts again. It took 5 pulls, but I started again. This time I mowed 3 mins before it quit.

If it doesn't sound right, take the 20 min to do your own test. Keep in mind that my push mower always starts cold on one pull even after a 6 month storage. When hot it is usually one pull or two at the most two. I also did not dump the gas in the float bowl.
 
#18 ·
600 EFI Fuel and Oil Consumption

I found this YouTube video on the 600 EFI thread with accurate fuel/oil consumption.

The oil consumption is roughly 15% less than what I have in the chart.

The 174 mpq matches 16.3 mpg in the chart, which is 1 mpg off from the consumed 15.2 mpg.

My hope was to reach within +/- 1 mpg which is close enough in my opinion.

Don't mind all the numbers for now.

I am using this as a real example to explain a principal in the next posts.

2021 Ski-Doo Expedition Sport 600 EFI

15.2 mpg @ 174 mpq

73 miles
4.8 gal of gas
0.42 quarts of oil

Decrease in oil consumption

100 / 147 mpq = 0.680 quarts
100 / 174 mpq = 0.575 quarts

* The 147 mpq was taken from the chart @ 15.2 mpg

( (0.575 / 0.680) - 1) x -100 = 15.5% decrease in oil consumption

Increase in distance per quart of oil

An increase from 147 mpq to 174 mpq = 18.4% increase in distance
( (174 mpq / 147 mpq) - 1) x 100 = 21.4%
 
#19 ·
Which means more?

Percentage decrease in oil or Percentage increase in distance?

The oil consumption shown in the chart is higher than I would like out of two stroke, but I based it off of the 800/850 E-TEC which also works for the 600 and higher engine cc.

BRP had planned on a 40% increase in distance which works out to be 28.5% decrease in oil consumption.

From a marketing standpoint, one may assume the 40% is more marketable. But this is a flawed assumption, because it also means having to back further from a claim as it was done for the release of the MY2017 G4 850. So marketing had nothing to do with it.

Note the calculations in the 600 EFI post that showed a decrease in oil consumption was more involved than an increase in distance. Think about when you are riding, what does a 28.5% decrease in oil consumption mean? It is not tangible without using a calculator.

To get a 40% increase in distance, then off the top of my head I can figure 100 mpq will become 140 mpq. On one quart of oil I will travel 40 miles more than 100 miles, hence 140 miles.

Even with an odd number like 147 mpq it can be rounded to 150, drop the zero and multiply 15 by 4 to give 60, then add 150 = 210 mpq which is close enough to 205.8 mpq.
 
#20 ·
It is all about doing fast and easy calculations

We all have a range for when riding hard with our buddies at say 13-14 mpg, and riding slower with the kids at 15-16 mpg. Seasoned riders will consume/guess for different snow conditions without even thinking about it. So fuel consumption is a no brainer.

All riders that I know will have the trip A or B set before each ride to count the miles ridden. Fuel consumption and miles ridden are two values that are guaranteed for each ride. This leaves only mpq. With two typical types of riding, hard and slow, only two numbers are needed for the respected oil consumption in mpq. For example, 13-14 mpg @ ~120 mpq, and 15-16 mpg @ ~170 mpq. Don't worry about accuracy because it doesn't matter. If you have a sled that gets 18-19 mpg, then add one more point for a total of 3 simple mpq numbers to remember.

In the example below, note that I am low balling the oil consumption. The reason is the chart is so rich/high in oil consumption, that I can afford to error on the wrong/low side. For example the chart shows 13 mpg @ 102.7 mpq. An increase by 18% such as with the 600 EFI example, brings it to 13 mpg @ 121 mpq. Also note that I am using rounded numbers, because it is more about the relationship between fuel and oil consumption.

Example:
13-14 mpg @ ~120 mpq Hard riding
15-16 mpg @ ~170 mpq Light riding

Let's use some simple numbers and take it step further. Assume the same hard riding @ 13-14 mpg @ 120 mpq. Go 60 miles and stop for gas. Fill up with the usual 4+ gallons and the oil tank is down a half a quart. Your riding partner on a 800 CFI Polaris with a mechanical oil pump puts in just over a gallon, but consumed only half the oil. That is completely in the opposite direction with too little oil. I don't know if you care about the Polaris, but you may end up towing it, then overheat the engine and blow a belt doing it for the savings of a few dollars in oil. Try towing a car with a car. It ain't good on anything, and no better on a sled. You know how it goes, Ski-Doo uses too much oil and the Polaris works fine until the engine quits. This goes both ways, but I am merely talking about oil consumption. It can also be a sled in your fleet that someone in the family is riding. The point is with only a couple of numbers you can square away the sleds that are running good, and point out those that are in the left field.

The 600 EFI example gives a good clue on much leaner in oil we can go while remaining on the safe side. The calculation is easy by simply adding the percentage to the mpq. For example an 18% increase in distance to 120 mpq gives 13-14 mpg @ 140 mpq. I purposely error on the safe side with the 18% compared to BRP's initial 40%, but you can play it however you like. If the sled is out of warranty then the limit is when the engine quits and your pocket book for a shortblock. With a sled in warranty, then you can work with the OEM to correct a sled that consumes remarkably too much oil. In other words I hold to the chart for a sled under warranty.

This thread has never been about having to use a calculator on the trails. It is all about the relationship between fuel and oil consumption, and how to work it easily at the fuel pumps.
 
#21 ·
Graphs!!!


There are graphs to be seen. I began this thread without them, and then they were. When I first saw the first one for the 600 E-TEC, I found the the consumption did not match what I had worked out, but the concept was the same. I already knew that I was on the right track with the relationship between oil consumption and the load in terms of fuel consumption, but this was a pleasant confirmation of sorts.

The second one I found on my hard drive looking for something else, and thinking where did that come from??? I am pretty sure if not confident that I found both on DooTalk. Considering that I have been on DooTalk for over 10 years, and that I would find one of those needles 4 times a years, that makes for many needles to find in hay stack. In other words, when I find these needles, I keep them and eventually share them so that no one needs to rely on such luck to find them.

Colorfulness Slope Rectangle Triangle Line



The second one is a PDF file, so while it probably will not show, it is still there to click or download. From my understanding and the early date it was posted on DooTalk, this was an original oil vs fuel consumption for the 600 HOE. I do not know how the 600 HOE (E-TEC) has evolved with the oil consumption, but the latest 600R does not follow the same consumption. As far as I know, the later 600HOE have grown in power and in oil consumption. I believe the same to be true for the Polaris and Arctic Cat 600s in the same late 2010s. Sometime around MY 2016+ (MY = Model Year), power output and oil consumption has risen. It is my understanding that the 600 HOE had already grown high in power before it was transformed into the latest 600R. Only the OEMs know what changes they made, so take what I am saying for what it is worth. If ever you find someone from BRP who is in the know, then you have everything that I know to ask the better questions. Please do not say that I know, because I do not. Just say that you read from Daag44 that he/me has a strong suspicion, and that would be a fair paraphrase. Feel free to share your findings.

Just so you know my stance, there is no way in heck the 2016 600 HOE @ + 120Hp has the same low power output of an 2009 600 HOE @ 115 Hp. These are two complete different engines when it comes to power output and many other upgrades. The power output from the Polaris and Arctic Cat 600s were also reaching above 120Hp, so they were all pushing the power closer to the limit while keeping emissions in check which is probably in the neighborhood of 5% from maximum power. So if maximum power at 7,900 rpm is 130 Hp, then 5% less is around 124 Hp.

The reason for the power output is that it is closely related to the oil consumption. In other words, comparing the oil consumption between a 600R and a 600 HOE requires to first compare the fuel consumption for load, and then the power output. There is no way to make an appropriate comparison without knowing these two values. It reaches further with maximum power rpm (7,900 vs 8,100 rpm for example), bore/stroke ratio and CR (Compression Ratio), but I do not need to reach that far for my own use.

All that I need to know is that higher load, higher power and higher rpm all require more oil. This is the conceptual part that is all I really need to know. So if I work on an engine and bump either of these three things, then I know to bump the oil consumption. I do not need to know by how much the oil should be bumped. I only need to know that it does.
 

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#22 ·
Oil Consumption Increase with Power increase

In comparing the early MY 2009 of the 600 HOE to the MY 2016 HOE and the MY 2019 of the 600R, they all have different power output. To me it appears that BRP make more power while pulling it down to a lower rpm. Arctic Cat and Polaris both had higher running rpm until I believe Polaris raised the stroke of their 600 to reach a 650 with an equivalent square bore/stroke ratio as the Ski-Doo 600 that began with the 600 HO Carb on the MXZ for MY 2003. It took nearly two decades, but Polaris would eventually copy what Ski-Doo did for the 600 and eventually with the 850.
 
#23 · (Edited)
Good on you for putting this much thought into this Daag! You are one intelligent individual on many levels.

To be honest, yes my 850 drinks a lot of oil but if it can go several thousand miles without blowing up, the oil isn’t too concerning to me. Reliability is my number one priority so I can start and finish with the same sled and if that means that I burn more oil -so be it!
 
#24 ·
Daag44, see post #6.
This guy did dyno test of different oil/fuel ratios on a motorcycle, it is very informative, it most probably translates to snowmobiles, the golden ration will probably different for each application tho, but non the less should all be close in the same ball park.

 
#25 ·
Thanks for the kind comments.

Alain, I found the full version which apparently was written by Spanky @ Motocross.com .

Pre-mix 101
by Spanky @ Motocross.com


I also found another premix 101, one written by Rick Sieman who has authored columns for different magazines and written a couple of books.

Pre-mix 101
by Rick Sieman

Monkey Butt!
by Rick Sieman
Tales of dirt bike riding and magazine publishing in the 70s and 80s in Southern California.

The Last Ride
by Rick Sieman
 
#26 ·
Fuel / Oil ratio for Outdoor Power Equipment (OPE)

FYI: OPE is the same as Hand-held Power Equipment.

For any OPE including my Lawnboy mower, I use Stihl 2S oil because it works for me and I have no reason to change. I run them all on 45:1 regardless of the equipment or what year they were built. If I run an old Homelite saw that called for 32:1, I am still running the same 45:1 ratio. I would prefer 40:1, but most work I do is light and there is an amount of idling that causes the engine to load-up in oil. I operate a hedge trimmer at half speed using the hot start button, so I don't need more oil. This also lowers the noise and wear on both the engine and the trimmer. I could use 50:1, but I prefer more oil for my saws. This is how I have chosen 45:1 as a compromise.

If I plan on cutting logs for extended period, then I am bumping the oil consumption straight into the saw. If I didn't think to bring a syringe for easy measuring, then I pour it in as a guess. My range is ~45:1 to ~24:1, so whatever mix I get with a guess will be better than the 45:1 and there can't really be too much oil. I have my saw tuned down a hair to error on the safe side, so if decide to tune it up for a large job, then I am taking more care for the mix to reach somewhere near ~24:1

The gas tank on my Stihl 026 holds about 460 ml of gas. At 45:1 it will have roughly 10 ml of oil (460 / 45), ~14 ml @ 32:1 and ~19 ml @ 24:1 . So it needs +4 ml for 32:1 and +9 ml to reach 24:1 . If I don't have a syringe with me, a full cap from a Stihl 100 ml 2S oil bottle is ~4.5 ml, so adding two caps reaches 24:1 . None of this needs to be precise. It is more important to find your own range than seeking accuracy. For example, if I fill the caps with only 3 ml and reach ~30:1, or if I eye ball it and reached 20:1 , then I am good with it. Anything is better than my usual 45:1 for the saw to be spending two hours at wide open throttle and full load. It will work on 50:1, but it will wear the rings and LRB faster. Just an hour of constant high load may be the equivalent to years of light to medium loads. And if I uptune the high speed jetting to get it singing, it is reaching near 14,000 max rpm! The saw will be cutting a lower rpm, but the max rpm is the measure for the tune.


State of Tune

Many years ago when I first joined DooTalk and leaning about the ratios from all of you guys, I struck gold in the YouTube comment section where a gold certified Stihl technician provided a comprehensive explanation for how to tune a saw. On a saw that was rated for 14,000 max rpm, he would tune it down by about 500 rpm or maybe it was 250. I had a copy and since lost it, but it does not matter since I remember the key point which turns out to be relatively common knowledge in the saw world, so no big secret. I mention it to make a parallel between fuel/air and fuel/oil ratios.

Once a range is in mind, it opens doors to a whole other level of understanding and possibilities. The 600 HO Carb is a perfect example. In Feb of 2004 an uptune recipe was shared on DooTalk with Optimizing your 600HO. It was one of the hottest and best threads around, and still holds its own today. The problem back then, BRP were playing with low oil consumption and a new method of adjusting the oil consumption, so the consumption was all over the place. An optimized 600 HO that was good down to -20C (-4F) could also run exceptionally lean in gas and oil at -30C (-22F). A carb that gets optimized is typically done with the MJ (Main Jet) which only covers the high end which is used maybe 1-2% of the time. Most of the time a sled runs in the midrange, so with no needle jetting change it will run crazy lean in both gas and oil. BRP got rid of both problems with the E-TEC. The 600 EFI still has a mechanically driven oil pump, but BRP ensured that it was set right for enough oil to compensate for an acceptable range.

To know what that a particular rpm sounds like, divide the rpm by 60 to convert to Hz and use an online tone generator to hear it. The Hz can be multiplied or divided by 2 to reach the next octave for whichever one sounds better to your ear. I record the saw on my phone, then find the matching Hz using the tone generator and multiply by 60 to find the rpm of the saw.

Online Tone Generator

Revolutions Per Minute to Hertz Conversion

By the way, the syringe that I prefer is the 10 ml one offered at the drug store for free. Not because it is free, but because the plunger is only plastic. Those with a rubber seal at the end of the plunger are a PITA to use, so I don't want them.


Oil Brands

I enjoy supporting the aftermarket, but when it comes to 2S oil I stick with OEM. I could use other brands, but I not running those which have 100:1 on the bottle. In fact, any brand that boasts such high ratios is a brand that I ignore/avoid. In the following excerpt, note the different ratios 50:1 40:1 and 32:1 which is music to my ears.


Below is what BRP/XPS has today on July 18th of 2022.

2T Small Engine Multi-mix Synthetic Oil
<Multi-mix formula, can be used at 50:1, 40:1, 32:1, follow manufacturer recommendation. | Formulated with premium anti-wear additives, optimized detergency, extra corrosion protection and full synthetic base stocks for long lasting small engine protection and performance. | Low pour point is suitable for all season use. | NOT for use in large 2-stroke engines such as snowmobiles or outboard marine applications.>


OEM or Aftermarket 2S Oil ?

I am not planning on making the switch from Stihl to BRP/XPS, simply because I have no problem to report with Stihl oil. If you have not noticed the irony, XPS is an aftermarket oil for the OPE. Considering that maybe 95-99% of OEM 2S equipment is being used with OEM oil, any problem with the oil will cause a string of issues or all out failures which would spell a disaster. These problems do happen, but they are caught before the disaster and taken off the shelf. So if there is ever a problem with those oils, the risk to me is next to none. My experience with aftermarket bar oil has cost thousands in repairs and lost days of works.

I use the same reasoning for sleds with the majority of owners using XPS for Ski-Doo. How many OPE owners use XPS? For me, Stihl is to OPE much like XPS is to snowmobiles. Although there is a big difference between the two. OPE are all premix and they all use the same 50:1 ratios on their oil bottles. Snowmobiles have four engine technologies, DI, TBI and SDI, and Carbs. Snowmobiles also have four different oil deliveries, Premix, Mechanical Oil Injection, Electronic Oil Injection, and one is a combo although no longer in production. For example, I am confident in the Polaris oil, but do I want to use it in an DI E-TEC? I do not know the specific needs to a DI, nor what range/tolerance BRP has for their electronic oil pump and oil consumption mapping.

This last section stems from a recent oil thread where the gentlemen was told that Klotz was better to keep the exhaust valves cleaner. For all I know it may actually keep them cleaner, but my question is, at what expense? This is far too narrow for me to consider one high quality 2S oil over another high quality 2S oil. Assuming an oil that keeps the exhaust valves clean can also keep the rings and grooves clean of carbon deposits, what are the affects on the gas impregnation of a DI, or the effects on the LRB (Lower Rod Bearing)? I do not know, so how can I stand behind my laptop and suggest any other oil? What I can do is focus on the things that I do know such as the importance of the LRB.

For the exhaust valves, BRP have written something to the effect that if they do not get exercised often enough, then they will build-up with carbon. By the way, this document is available at the same place to download shop manuals. Whatever BRP has in their oil, no matter how small of a difference, the recipe between the additives, mapping and needs of the DI engine needs to work to keep the warranty claims down. If it does not work, then either the recipe needs to be adjusted or quit selling two strokes. Twenty years ago, the outlook for two strokes was bleak. Who would have guessed that in 2023 we could buy an OEM turbo two stroke from two manufacturers?

One last though on the OEM oil with a comparison to OEM rings. Can you find an aftermarket ring that is both sized and trued to the same level as the OEM ring? I will keep using aftermarket pistons and rings, but I am not expecting anywhere near the same quality. I don't even expect them to meet one of the two qualities. When the OEM chooses a company to make their rings, they cannot afford to be filing each ring during production, yet we have to do this when we rebuild our engines which is a real PITA. And we need to watch YouTube videos to see how others are doing this and what tools they are using.


The 850 E-TEC

There are too many things we do not know about oils, but focusing on the things that are well known will go a long way. The 850 E-TEC is a perfect example with some that are obviously using too much! On an 850 that I was to take the clutch alignment, when the owner started the sled it blew so much smoke in the garage that could fit multiple large trucks that we needed to open the door and walk out to breathe. That and when taking off with an 850 or any sled that leaves a dark trail in the snow, it is probably consuming too much oil!!! This is another part of this elusive range that I have referred to, and the reason for making a special mention for OPE.

If you are one of those 850 owners that consumes too much oil, I imagine that you have already tried to address the problem by asking your local BRP dealer. I assume that you quickly found how difficult that could be. Some BRP dealers have a remarkable level of competence that there are no such issues. For the others, it can be at best a hit or miss affair, and at worst a problem that is not even acknowledged. The four problems that I have found difficult to get addressed by a BRP dealer are: 1. Too much oil consumption, 2. Too much belt heat, 3. Engine temperature too high, and 4. Too much vibration. I am just guessing that maybe one out of 500 will have any of those problems, but if one does then BRP needs to provide a means to get them addressed.

Building a oil consumption relationship between OPE and snowmobiles is what I believe to be one more piece of the puzzle that can help to break down the barrier between the two which complement each other. The goal of this thread was to provide the tools to work though these problems. So even if my first post might be in the left field, I included all the tools needed to fix it.
 
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