My working partner will drive a long way out of his way to get E0 90+ octane gas for all his OPE and runs only the best, most expensive he can find. Me, I use 87 octane, with decent gas stabilizer in it in all my tractors and OPE. I have a 20 year old JD 425 gas, and all kinds of other older OPE and narry a problem at all. I do sometimes use Trufuel, simply because I don't use a weedeater or chainsaws enough to warrant the mixing hassle, but I still use a lot of 87 gas to mix, so it's not all the best stuff. I gave 90+ a try one whole summer at my pal's insistence and never noticed any difference at all. He still swears by the high octane stuff and I still use the low and we have 4 of the JD's between us, go figure.