Our official oil thread! When motorcycle guys ask me or start talking about it I laugh because their bikes are much more likely to be stolen or wrecked long before any effects of the wrong oil would be realized. I've always seen folks use regular cheap oil in old bikes and never have any problems. The Lucas Oil Stabilizer is some pretty good product I've used before and been happy with. My Rotax in the Aprilia always gets expensive oil because it's expensive to fix! The old bikes get whatever I have laying around as long as it's pretty thick viscosity. There is no way I could put enough miles on an older bike to test out any oil.
If I enter in any poker runs or back country rides on one of my old bikes I'll surely come revisit the info here to prepare the bike with the best.
On one of my two stroke dirtbikes I was surprised how clean the last oil change came out... until all the sediment came out at the end! Oil is cheap compared to the engines they protect. Great info to know for the older bikes.