Stihl 251C - Motor Oil ?

[MikeStihl]

Greetings from Boston, MA!! Just bought a Stihl 251C - getting familiar and doing basic maintenance.

Not sure why, but I can't find any info on how to change the motor oil on this saw. Type of oil, quantity, frequency, oil filter - no info anywhere in the manual or elsewhere, so far.

What am I missing here?

--
Mike

[lxskllr]

It's a 2stroke motor. It gets it's oil from the fuel mix. There's no reservoir of oil or crankcase filter.

Welcome!

[barbender]

 Welcome, Mike!

 Your Stihl 251C has a two stroke engine, that requires 2 stroke oil premixed with the gasoline. The engine doesn't use crankcase oil like an automobile or a riding lawn mower engine.

 Wherever you bought your saw should have Stihl 2 stroke oil. It will have instructions for proper mixing ratio on the bottle.

[MikeStihl]

Thanks guys!  So the wristpin, crank etc. pick up whatever oil residue they can and are otherwise robust enough to survive in that environment. Very elegant design!

Much appreciate the explain!

--
Mike

[sawguy21]

Welcome to the scrum! Did you not get an owners manual with the saw? It is very important to mix a quality 2 stroke oil with clean fresh gas to ensure performance and service life. I won't get into brands and mix ratios. ;D

[Ianab]

Thanks guys!  So the wristpin, crank etc. pick up whatever oil residue they can and are otherwise robust enough to survive in that environment. Very elegant design!

Much appreciate the explain!

--
Mike

Correct. Because the air / fuel mix is sucked in through the crank case there is always a mist of oil inside the case when the saw is running. This is enough to keep the bearings and cylinder walls lubricated.  Fastest way to kill a saw is to run it on straight gas. No lube and it will soon seize up. 
This also explains why the motors can be made so light ( few moving parts), and be run in any position. 

[HuckFin]

If you bought your chainsaw new from a Stihl dealer, they will double your warranty when you buy a six pack of their HP Ultra oil mix.

[MikeStihl]

@sawguy21 - I got the owner's manual and read it. I suspected there was a reson for no "oil change" mention, but ...jupming to conclusions - I try to avoid that with technology. I'll start with a premixed 50:1 from a big box store and will get to mixing my own next season.

@Ianab - hearing from someone involved with JP is a rare treat. Thanks for the expanded note! 

[lxskllr]

If you aren't cutting a whole lot, sticking with premix wouldn't be a bad idea. It burns cleaner, keeps longer, and all you have to do is pour it. It can get expensive though if you do a lot of cutting. You'd have to make the economic decision for yourself.

[MikeStihl]

Not a lot of cutting, really. Several medium caliper oaks a year, for firewood. Premix makes sense to me too, right now.

Adding Stabil to premix - good/bad?

[lxskllr]

Nah, it isn't needed. SEF brand advertises it keeps for five years in a sealed can, and two years in a gas tank. I'm sure all the brands are similar. Keep an eye out for Aspen. Maybe check their website and see if anyone near you sells it. That and Stihl Motomix burn the cleanest, but the Aspen seller near me sells it at a very competitive price($27 for 5L last year). Motomix is eyewateringly expensive.

[thecfarm]

Got chaps?  ;D

[KEC]

I would say that when you mix your own fuel to use Non-Ethanol. And put some in your car or pickup first to purge the pump and hose at the gas station. I can't bring myself to pay the price for pre-mix.