I just go by whatever is recommended in the manual.
STIHL MS 500i Oil Mix Ratio
- Thread starter Toneman
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Anything else is anecdotal here say, and believing in that sort of thing is what keeps people firmly in the dark ages , running a saw on near double ratio with an expensive oil will easily cost the price of a new saw over the life of the saw, and from what I’ve seen they will wear out the top end and the piston is like a sausage being thrown down a hallway. Those that claim bearings have failed because of improper lubrication need to show and prove how they came to that conclusion , the most common reason for bearing failure is abrasive contamination. Have a read up on the causes and diagnosis of failures here,
https://www.timken.com/pdf/5892_Bearing Damage Analysis Brochure.pdf
LegeaDejului
ArboristSite Lurker
You do realize Stihl themselves, on their own site, says to use 50:1 if using their oil, and 25:1 if any other brand of high quality oil?
https://www.stihl.com/fuel-mix.aspx
Also, the extra oil we're talking about isn't for the piston and rings, those can do fine even at 50-80-100:1 if jetted right. Sliding motion requires very little oil, and the quality of it matters, but its the rolling motion of the bearings that needs oil volume. There's a reason why saws ran at 50:1 for hundreds of hours have spotless pistons and rings and wobbly/noisy bearings compared to the same saw type ran at 40-32:1
The claims of bearings going because of lack of lubrication is anecdotal at best, thinking there is the lack of lubrication in a total loss system with a constant supply of brand new oil is dreaming, ball bearing races just need a microscopic amount of oil to function without failing, any more is just excess being pushed away from in front of the bearings, the contact point of the bearings is the only place the lubricant is required, & that is measured in microns, that's why foreign debris is the enemy of bearings & chainsaws are surrounded in the stuff everyday.
As RPMS rise that oil that's constantly replenished is leaving as fast as it comes in or worse depending on the ratio. Two strokes are very minimally. Lubricated compared to a pressured automotive lube system, which is why they use ball and roller bearings in the first place.
On top of this we now have strato saws which burn less fuel, which means they run hotter and have less pil traveling through the motor.
The oil film on a ball bearing race only has to be microns thick to lubricate the bearing, the quality & viscosity of the oil is the important part, using crap oil which can't provide lubrication under pressure will not improve wear resistance even if more oil is present.
LegeaDejului
ArboristSite Lurker
Pls document yourself on why oil volume is important for rolling wear reduction instead of trying to guess what's going on.
You mustn't understand real good , or know what microns are.
Actually good oil isn't cheap and burning that much of it is detrimental to ones health, last I heard you can't buy a new set of lungs, so less is more & they are still making chainsaws.
You pulled that microns comment out of your azz.
A motor ran on plenty of crap oil will last an astounding amount time. In fact I would wager longer than the same motor ran on scamsoil at 100:1.
Actually two cycle oil is pretty damn cheap.
Actually no I didn’t,
https://www.sciencedirect.com/topics/engineering/minimum-film-thicknessHeres the data for optimum bearing oil film thickness, and guess what? It’s in microns, you blokes are pissing your money and oil away on some long held fallacy from the two stroke dark ages
Not here it isn’t and I’ll wager you can’t get a new set of lungs on the cheap
LegeaDejului
ArboristSite Lurker
What do you got to gain by spreading misinformation? Fascinating really. First pls read what you quoted yourself, nowhere in that article they mention "optimal film thickness". Because there's no such thing as optimal. Did you even bother reading it? Why do you make **** up? Microns? Where? The entire article is in mm. Why do you think ball bearings in general use a **** load of grease? Because more lubricant reduces adhesive wear. And that's also explained in the same article in regards to oil. But wait, there's more.
"When the minimum film thickness exceeds say 2.5 × 10−6 m the coefficient of friction is small and depends on no other material property of the lubricant than its bulk viscosity. This type of lubrication is called thick-film lubrication. It is the simplest and most desirable kind of lubrication to have."
Empirical data from mechanics also support this claim. More lubricant, less wear. I'd stop posting if I were you, this is embarrassing. I came here to ask a question about my new saw, having to deal with inflated egos wasn't in my plan. But it seems like on public forums there are alot of people playing the game of acting smarter than they are just to prove some wives tale they religiously believe in, only to prove themselves wrong. Funny.
Bravo, you googled up something that supports what you said, except it doeant. The problem is the machines listed in your link either use grease or pressure lubed type system. In addition most of those bearings are not ball or roller bearings.
As far as emmisions go the unburnt fuel is of much greater concern than oil.
Regardless we now have emmissions compliant saws that don't out out anywhere near the emmissions of the old stuff.
Yet another straw man.
Exactly! He didn't even read the link he posted or didn't understand it.
It is actually you spreading the old wives tales, then projecting as a defence of it, there are a thousand microns in a millimeter, and the data shows measurements to 3 decimal places below a millimeter optimal just means and adequate amount where anymore is just wasted, having the bottom end swimming in oil is total waste when the oil film thickness only has to be microns thick, the bearings don’t need that much , read the data and understand it before running off on a typical rant of the forever ignorant,
Man, I think you need to read what it says and then think about it for a bit.
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