I have an old stihl 025and a stihl ms 290 that I've had forever. Currently thinking about a 620pw echo but didnt pull the trigger just yet.Countless cards cut with these 2 saws.i always ran stihl 50:1 mix with no problems.however there had been a half dozen times over the years I was out of stihl mix so I would mix up a few gallons on gas with mercury quicksilver tcw 3 outboard oil at 40:1.the saws didn't mind and still run great today.just wondering of any body else besides me has done this.oh and merry Christmas to everybody!
Saw probably won't care between 50:1 and 40:1. Use good oil and you will be fine, assuming you have it tuned properly. I run 32:1 in all my yard stuff to include trimmers, all my saws and hedge trimmers. I run Red Armor oil which is one of the better ones, even if you run on the ragged edge of insanity. I always ran 40:1 before that. 50:1 in my opinion is an EPA thing. One year Stihl recommends 40:1 and then the next it's 50:1. They produced the same saws those years and didn't have any oil reformulations. So why the change? Eggshooterist is kind of a resident expert on oil here.
40:1 in 'em all, ported and not. Even milling @ that ratio with excellent results as I've tore that saw down many times to check the internals for wear and residual oil.
For the average firewood hoarder, 40:1 any good grade of OPE oil...but NOT outboard oil...yeah yeah I know, you got away with it, but sooner or later that will likely bite you in the arse. You already are...you are subbed now...
I run stihl 40:1 silver bottle. Years back an OPE dealer told me to run 50:1 but mix with two gallons of gas so a 40:1 ratio. I use 91 or sometimes 93 octane. I know a lot of guys run non E fuel, but ive never had an issue using "normal" gas for many years.
I put a new muffler on the 025 over this past summer.piston and cylinder look like new after 20 plus years and 100s of tanks of fuel.that outboard oil sure didn't hurt anything
