What are the latest theories on adding 2 stroke oil to both diesel and gas engined old Cats, is there any benefit to be had, or is it a waste of time and money? Most my old girls sit for a long time between floggings, so I've used some oil in the gas Cats tanks just to try and reduce rust issues, but I remember folks talking about valve lube benefits too, but can't get the topic search function to work on here.
Thanks

Over here I have been using 93 octane with good results, but some places sell "lawnmower Gas" which has no methanol in it and works good.

Here in Dreamland I use my 2 stroke chainsaw mix in my pony motor tanks, figuring they always have rust issues, and used to use the higher octane gas because I was told it stored much better than regular gas, the downside was my Stihl MS390 chainsaw started getting hard to start and it took me a couple of years to work it out, even after having the local Stihl workshop investigate the issue who fitted a new aftermarket carb for me.

I went back to using regular gas to mix my 2 stroke fuel and that has really helped the problem, it "only" takes about 10-15 pulls on the cord now to fire that saw off, whereas previously on the high octane 95 fuel it would be 35-45 pulls on the starter cord with choke on, before I got the first pop. There is no doubt my saw is a dog, not a Cat....

Sounds like the carb is way out of adjustment, 5-7 pulls starts all my saws.

not to start a chainsaw discussion, but I got rid of my hard-starting Stihls and replaced them with an easy starting beautiful Husqvarna. day and night difference.
 

Just my 2 cents. Quite a while back I noticed all my rope start gas powered engines were getting harder to start.I get supreme gas now and put StaBil in my gas can.My cussing has completely stopped.Sure has made starting and life easier.

Sounds like the story of the hillbilly that went to the hardware store to buy a chainsaw as he was tired of cutting the wood by hand.  He bought a new chainsaw and left the store only to return a few days later to complain that the chainsaw was no better than his old hand saws.  The clerk said lets go out behind the store to the wood pile and check it out.  They went to the wood pile and the clerk took the saw, jerked the starter rope a couple of times and Varrrrrrroooooooooooooooooom Varrrrrooooooooooooooooom put put put to which the hillbilly said "what's that noise"??

Hard starting chain saws are not worth having. 

Back to the gasoline in pony engines.  I have always used PB Substitute after lead was removed from gasoline. It is good for the valves and when I let gas sit for a while I use Sta-Bil in it and I believe it really helps.  I use regular without ethanol.  I learned the hard way what can happen using unleaded gasoline in an older engine and ruined the valve seats and guides in a pickup in under 1000 miles. Hardened valve seats are an alternative as Neil pointed out.

Mike wrote:

What are the latest theories on adding 2 stroke oil to both diesel and gas engined old Cats, is there any benefit to be had, or is it a waste of time and money? Most my old girls sit for a long time between floggings, so I've used some oil in the gas Cats tanks just to try and reduce rust issues, but I remember folks talking about valve lube benefits too, but can't get the topic search function to work on here.
Thanks

that's a good question Mike and i think the results will be mixed...
- i wouldn't add any kind of oil (additive) to diesel unless it was an injector cleaner etc....diesel is already a light oil...
-here in North America...the latest fashion is Gasoline Stabilizers...i've tried some and i can't really see any difference in fuel and tanks that have sat awhile (thru winter etc)
-your mileage can and will vary..
 

I use Aviation fuel 100 Low Lead in all of my gas powered engines like lawn mowers pony motors and the gas CATS. Most sit for months at a time and I have no issues. It also smells better than regular pump gas. I haven't checked cost this year but last summer I was paying around $4.80 gal.