What gas for an old 420c?

[Fallon]

Getting near needing to fuel up my new to me 420c for the first time. I'm up here in Colorado at about 7,000'. A lot of people drop a trade of gas here compared to elsewhere due to the lack of oxygen. I'm lucky as my local station has ethanol free (92 octane I think) in addition to the usual 85, 87 & 92. I use the ethanol free for all my small engines (side by side, pressure washer, generator, etc. Any reason not to keep using the ethanol free? It is more expensive, but I don't burn a lot & hate having to needlessly wrench on things.

As this engine predates unleaded gasoline, do I need to worry about that? Any additives I should be putting in to keep valves happy?

[Jim B]

I run 87 octane with 10% ethanol in all my gas engines, not many places around with ethanol free around here. I don' have any problems with it. I don't use additives, like lead substitutes, other than maybe a shot of Seafoam or Marvel Mystery oil now and again the same as I did with leaded gas. The key is to keep you fuel system clean, be it gas or diesel.

[Lavoy]

You can add a little lead substitute if you want. You likely aren't going to put on enough hours to cause much valve recession. Octane is a waste of time on these old girls, probably 7 to 1 compression maybe.
Lavoy