fuel mix, new stihl

[Mark Bolam]

Things have moved on a bit mate....

[Catweazle]

There is a danger of two-stroke engines running weak if there is too much oil in the mix. The extra viscosity coupled with the extra volume of the oil means less petrol per bang, which means weak mixture, overheating and possibly detonation.

 

I still have a lot of information on different oils from my two-stroke bike tuning days, one of the most important properties is film strength and even the best modern synthetics can't beat castor oil for this although they score with friction modifiers, octane boosters and additives that make the mix keep much better without gumming up your carb.

 

Chainsaws aren't highly tuned, so the oil doesn't have to do much, I'll bet Stihl and Husky are both pretty basic oils.

[Buzzsurgeon]

Use Aspen Fuel! Kind to your lungs

[likeitorlumpit]

  flaming-ace said:

its the way my granddad has taught me and as with the old saws it says to mix at 25:1, he thinks that there isnt enough oil in a 50:1 mix, and hes never had a saw seize up on him

 

We had a husky seize up on us

Husky said we were using too much oil in the mix

You can't win

[gensetsteve]

  Catweazle said:

There is a danger of two-stroke engines running weak if there is too much oil in the mix. The extra viscosity coupled with the extra volume of the oil means less petrol per bang, which means weak mixture, overheating and possibly detonation.

 

Chainsaws aren't highly tuned, so the oil doesn't have to do much, I'll bet Stihl and Husky are both pretty basic oils.

 

I have heard this before. It makes sense and have gone with it. Use 50:1 and make sure the fuel is fresh and freshly mixed. If you leave some mixed on the shelf for a few weeks I think u can cause problems.

[daveindales]

this was quite an old post. I have used the husky oil and have had no problem with the saw

[chaffey]

They're not bothered what oil you use. They would take the saw to pieces in a warranty situation to see if they can see if it had been running lean etc. By the way i was told not too long back that i should be using the green two stroke in my four mix engine not the red. I was told it would do for the rest of my kit as well. Anybody else been told this?

[Ironbark]

I'm pretty sure that a manufactuer cannot specify a particular brand of oil for their product, only a specification. If you look in the handbook it will specify the oil requirement. As long as you use an oil that meets this standard, they cannot refuse any subsequent warrantee claims.

[blazer]

I run on the makers recommendations, Stihl claim theres is ok at 50-1 then I run at that no probs. 2 stroke engines and their fuel/oil has changed alot over the years. My only caution is not to fill up from somebody elses can, when offered on a big job.

 

I have heard of problems in artic conditions where the locals run on a weaker mix for 2T snowmobiles etc.

 

I often wonder if left for a long time the oil/fuel can separate, in the early 70's Yamaha bike race teams would remix up fuel fresh for each day - I used to 'help' dispose of the old mixed fuel with a free fill-up when with friends in the pits.

[aob9]

  Buzzsurgeon said:

Use Aspen Fuel! Kind to your lungs

 

Agree, and I've read elsewhere that Stihl have endorsed same, well at least they said it won't invalidate warranty. Here it is.....

 

http://arbtalk.co.uk/forum/aspen-fuel/17741-letter-stihl-regarding-aspen.html