40 to 1 or 50 to 1

[D._Frederick]

What would give my 372 the best engine life?

[Larry]

My 272XP just had it's tenth birthday and still runs like new.  Started it off with Stihl oil and later switched to Husky black bottle when it came out.  Mix has always been 50 to 1.  I don't use the saw a lot...more like a weekend logger.

Good luck with your new saw D...the only saw out there that is better than my 272 would be a new 372. ;D

[rahtreelimbs]

A lot has been stated on this subject. As far as I am concerned for the little extar cost go with 32/1. I have not run a saw long enough to see a difference however the little extra oil that 32/1 provides will undoubtable be beneficial!


At 32/1 my saws don't smoke. Use Mobil 1 MXT2, which is 100% synthetic.

[tony_marks]

what he said.

[pallis]

Yeap, 32/1 MX2T should do the trick. 

[tony_marks]

ive never hurt a saw using quality dino at 40 or 50 to 1.
but in my service i use cheap trimmers an such to avoid theft. the thieves dont bother a craftsman trimmer ,but will tear up u rack to get a stihl or other quality piece.
any way i use to have to replace this cheap stuff at least every other yr.
since i went with mx2t at 35-1... ive yet to have one of these cheaper pieces wear out on me. to me that was a significant indication that mx2t is superior to dino. jmo

[clyde]

evinrude did massive testing on two stroke engines back in the day.  You will make more horsepower with more oil all the way until spark plug fouling.  There is no advantage to running less oil.  32 to 1 is perfect.

[SawTroll]

A rather comprehensive test I read about some time ago concluded that more mix oil made the engine running hotter, which is probably not a good thing.....

[fishhuntcutwood]

I agree.  I run 50:1 with Stihl mix.  It's what I've always run, and without any problems and without too much smoke or heat, and it's what stihltech and stihl doc recommend, and these guys work on Stihls for a living, and I work with Stihls, so that's good enough for me.

Jeff

[clyde]

As you run a higher oil ratio.  You will run leaner on your fuel-air mixture.  This is what will cause the engine to run hotter.  You will have to richen up a bit.

[archerR80RT]

Oil burns hotter than gas, that is why it burns hotter with a richer mixture, not because it is leaner.   gary

[clyde]

if you go richer on oil you will run leaner on your gas to oil ratio, for sure.  If you run a lower oil ratio you will run richer .  the oil really doesn't burn in the cumbustion chamber.  it basically burns in the exaust system, or is trapped in it  or expells.

[StihlDoc]

When running 40:1 vs. 50:1 fuel/oil ratios you will not have any need to worry about temperature, horsepower and carb adjustments. The variance is so minimal you won't "feel" any difference. The differences show up as an insignificant change in data when running on a dynomometer and test equipment. The problem with richer oil ratios is with deposit build-up in the combustion chamber and exhaust port over a period of time. The optimum is to use only the minimal amount of lubricant needed to overcome friction. Any more than that is a waste of oil and can cause engine damage over time due to the deposits the excess oil creates. If the oil label states it can be used at 50:1 then mix it at 50:1 since that is the ratio the chemists and engineers blended it for. Two-stroke mix oils are made from a recipe of different oil types, special additives, and detergents blended at specific percentages for the type of engine design the oil is intended for.

[Frickman]

I run 50:1, with premium gasoline. I haven't had a saw blow up for a long time, other than those that were just plain worn out.

[spencerhenry]

i run stihl oil, used to run it at 50:1 just like it says. but my saws never run below 5500' elevation. last week i was logging at about 9700'. and sometimes i am cutting around 11,000'. the higher i go, the more i have to lean it out to keep the rpms where they need to be. my theory is that if 50:1 is good at sea level, and that is how much oil the system needs, when i turn the high speed screw in say 1/4 turn, i have decreased the amount of fuel, AND oil. but the crank is still turning at the same speed. i wont even hazard a guess as to a numerical amount of oil, but i now run my saws at around 40:1 or 42:1