OIL Again! Stihl Ultra

[klickitatsacket]

Well I have not instigated this one in quite some time, but I had a saw that came in last night to be checked over.
This is actually a modified saw we built. It is a MS440 with a 460 Big Bore kit on it. the Deck has been shaved .050 and is fully ported among other things.

http://i5.photobucket.com/albums/y186/klickitat/440_4486.jpg

This is a picture the piston after 5 hrs. of run time. The saw was run using 40:1 Stihl Ultra oil. Now the low end was beautifully lubricated, but as you can see the carbon is already building up on the piston crown and fairly thick. This is the reason I do not prefer synthetic or bean oils for daily use. This gummy thick resifue that sits and burns on the tops of the pistons and gets into the ring grooves does nothing but cause problems.

Now I know this is going to be a burr under a few peoples saddles but time and time again I see this with the synthetics and bean oils and just can not recomend them for daily use. I know there are tons of people that swear by the new synthetics, amsoil, and hemp granola mixes. the problem for me though is I just don't think the bennifits in the low end out weigh the problems in the top end.

I will also say that I have not tried all synthetic oils. I have had a little experience with the MXT2 that Ben walker sent me (thank you) but I did not get enough time on it to see what it is like in the long run. Right now I am doing well with Stihl, Husqvarna, or echo brand Dino oils at 40:1 and this is what we recomend to all of our customers unless they are using our saws for milling in which case we recomend 32:1

 

[sawinredneck]

Was it just carboned up, or was it scored as well? Just asking as I just switched over to Royal Purple.
Andy

 

[BostonBull]

looks pretty bad. I will be switching back soon.

 

[BostonBull]

and now.................opcorn:

 

[klickitatsacket]

There was a little touch of a score on the exhaust side but the owner admitted to leaning out the carburetor. No real damage. the scoring is so light that I am not sure it would be noticed for more than normal wear and tear on a work saw (just a little early is all). I will admit if it was dino oil the scoring would most likely have been worse. The synthetics do protect the low end quite well.

 

[klickitatsacket]

Jim, here I was being nice and keeping your name out of it. :biggrinbounce2:

 

[Lakeside53]

I see carbon like, that on almost every saw I pull down. It seems to get a "base" and just stay like that. Real question is whether the carbon is building up around or behind the rings.

 

[klickitatsacket]

The top is thick with carbon, way thicker than most saws I see unless there is a problem with a person running a dirty airfilter (again I will admit there is a lot of that) but on a saw that is taken care of this excessive by far. There was the same black goo around the rings. I used some Castrol Super Clean and a nylind brush to clean it out.

 

[Lakeside53]

Maybe it's an optical illusion, but have you shaved (rounded) down the top of the piston to the rings? If so, that could account for the crap in the ring grooves.
Also.. why run the ultra at 40:1? why not 50:1? it is significantly better at lubrication than dino...

 

[klickitatsacket]

The piston is domed, but I say that I do not see problems with dino oil burnign behind the rings with this design. The 40:1 I recomend but the customer decided to use the synthetic not me.

 

[Lakeside53]

It would seem to me that the top ring is exposed to flame front / combustion much more than on a "conventional" design.

I'm not disputing what you see.. just an observation.

 

[klickitatsacket]

totally understand what you are looking at and thinking. The thing is though, that I see this on flat top pistons as well.

 

[Canyon Angler]

interesting thread, thanks for posting up, klickit...

i suspect the key is how bad the rings get carboned up and start hanging up, etc., since eventually the piston will carbon up no-more ... right?

 

[NWCS]

i agree with Dean on this one. in my years of motorcycle engines and now saws i have tried all the fancy Castor oils and synthetics. i keep going back to Stihl oil every time and get much better results out of it. in my restored 1976 Honda CR250M i actually ran Stihl oil in that too. she held 220psi compression and the 2 years i owned the bike she never had a problem. even my race saws so far have run Stihl oil and pump gas, the same stuff my work saws run, same stuff my customer saws get tested with.. that also means the same ratio that i am just going to leave out of this thread.. this is not about ratio.

 

[bwalker]

That piston looks typical of most Stihls that I have seen regardless of oil. The jetting also looks to be a little off. Nail the jetting and load the motor a little more and it will clean right up.
This piston was run on synthetic for its entire life.

 

[klickitatsacket]

Ben, is that the MX2T?

 

[bwalker]

Ben, is that the MX2T?

Yep.