Thanks for posting that. It has evolved several times no doubt in the past 20 years since I first became familiar with it. They used to muse that a window screen could catch "some" 25 micron particles therefore you could call a window screen a 25 micron filter and not be lying. Baldwin is a filter company that's core business is making filters. They don't get more reputable than Baldwin.
That said does Baldwin really give a 4 micron rating? In the past Baldwin has always taken stance that particle counters are not practical to measure below 5 microns. I've seen Cat calling theirs 4 microns so maybe they are just figuring if it's 5 absolute it's bound to be damn good at 4? All of my trucks run the BF7635.
For the OP's issue with rust I think I'd be looking at a Filter magnet to grab the ferrous metal bits but again once in the tank you are pretty much SOL.
Yessir, I looked at Baldwin's data sheet on that particular Baldwin model and it says '4 absolute'. FWIW, your filter lists '5 absolute' so yours should be really filtering 98.7% of 5 micron particles. It'll catch some lower percentage of 4 micron particles and to lower %'s for even smaller particles.
It might do me good to look into the particle size matter, but I would not be surprised if their equipment is getting better. A lot of this is being driven by needing to maintain long term environmental performance of systems per the EPA and their Canadian equivalent. Hence the modern fault messages, finer injection sprays and controls, much more frequent filter changes, and threats to shut down your truck in so may miles if you don't fix something. (Not to mention the recent massive fines to re-sellers of delete kits.. but that is another topic...)
I'm pretty familiar with filter ratings....from performance auto work, but have been specifying parts for system and product designs for about 4 decades. Some companies (like Baldwin) you can trust IMHO. But like the Twinair spec of 'articles as small as 40 microns'... that jumped right out as NOT being a true filter spec. My god, you can see through the thing LOL.
Never thought of magnet for rust: good thought there. Looking at that, rust is weakly magnetic. Maybe a good powerful one would get most of it out... just keep it away from your credits cards.
BTW, since you run trucks, Diesel Pro, what diesel injector cleaner do you regularly use?
