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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 pages 17 and 18)

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
 

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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.
 

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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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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.
 

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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.
 

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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.

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

Don~
 

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Discussion Starter · #7 ·

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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.
 

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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.
 

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[.....]

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).
 

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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.
 

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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 you can click the link below for the source. 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.

Oil Migration Sheet - MaximaUSA

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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)
 

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Discussion Starter · #15 ·
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.
 

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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.
 
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Discussion Starter · #18 ·
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.
 

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Discussion Starter · #19 ·
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%
 

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Discussion Starter · #20 ·
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.
 
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