STIHL MS 500i Oil Mix Ratio
- Thread starter Toneman
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sbhooper
Addicted to ArboristSite
Run what it says to run. Quit playing little games with technology. 
Yes they run well on 32:1 ported and stock
stihl86
Addicted to ArboristSite
Good question.
HuskyP
ArboristSite Lurker
I suggest you contact a saw builder. Some who had seen the guts after running different mixes, an old timer.
thomasinvancouver
ArboristSite Operative
More oil than needed=Less fuel than needed
Keep in mind that everything you do to make a two stroke motor more efficient reduces the amount of lubricant the motor receives.
At 51, I wouldn’t really call myself an old timer. But of the hundreds I’ve been into, 50:1 isn’t enough. It’s fine on smaller old school engines, but not on stratos or bigger saws if you want the bearings and crank to last
HuskyP
ArboristSite Lurker
Nice! Is 40:1 enough to coat the bottom end?
It depends on the oil. From what I’ve seen, all 0pe oil isn’t the same. I usually recommend 32:1 because even most underperforming oils will still protect the bottom end at that ratio.
I don’t care to get into which I believe are good or bad in the open forum. Butts get hurt too easily nowadays
HuskyP
ArboristSite Lurker
Perfect 32:1 it is. That’s done. Thanks
I’d concern yourself more on the tune of the saw and sharpness of the chain than the oil content. 32:1 - 50:1 all work just fine.
A lean tune and dull chain will kill a saw far quicker than a few less drops of oil in a tank.
Too much emphasis is put on oil ratios and not enough on the other two.
I take the middle ground and go 40:1
A lean tune and dull chain will kill a saw far quicker than a few less drops of oil in a tank.
Too much emphasis is put on oil ratios and not enough on the other two.
I take the middle ground and go 40:1
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BEEN RUNNING OUR 500 SINCE OCT. ON THAT RATIO. DELIVER 55 CORDS OF SPLIT FIREWOOD ON AVERAGE A MONTH, BUT SAW CUTS MORE RNDS THAN THAT. BETWEEN 3 AND 6 CORDS A DAY.
FANTASTIC SAW. MAKES $!!
40 to 1 want hurt it but 32 to 1 may be problematic latter on
I was referencing non-adjustable autotune and mtronic saws in my above post also. Many of these newer saws have a heavier strato piston and because of the inherent design these saws also have about 30% less oil and gas going through the bottom end. I’ve replaced case bearings in quite a few with only 300-500 hours on them.
I'm of the same opinion.
KTM recommends something like 60:1 with synthetic in their 250-300cc dirt bikes and you hear way to many blow up stories from guys that run them like that.
Most guys do not consider a strato saw has much less lubricant flowing though it vs a traditional two stroke.
sbhooper
Addicted to ArboristSite
Just use a good synthetic and run what the book says. Amsoil works at 100:1 and I did it for years without issue. I run 50:1 now, as that is what the book says to run. 32:1 is just wasting oil as far as I am concerned. More is not always any better.
More blanket statements.
The average firewood cutter only puts 300-500 hours on a saw in his lifetime. Tree service guys put that many hours on in a year. And that’s about how long it takes to wear out 562 bearings at 50:1.
Start putting real hours on your saw and spending real dollars out of your pocket on repair bills and you’ll realize that
I always get a chuckle out of guys proclaiming Scamsoil 100:1 is the best thing since sliced bread because their saw didnt blow up immediately. That's a pretty low bar and pretty flawed logic.
Why one would want to run less oil in a engine design that's very marginally lubricated to begin with is beyond me. Then you have the new saw tech which runs hotter and uses less fuel, so its even less lubricated.
