OK, here is my 2 cents. I've tried a lot of different lubes on o-rings and a lot of the stuff was suggested by some of you folks on here in months past. I think that in static applications (you put it together once and it stays there until you disassemble next time), o-rings are pretty forgiving and will work with just about anything.But for dynamic applications, like piston seals, it is a lot trickier. But maybe it really isn't. I don't own one, but the Shoebox Compressor uses o-rings on its piston seals and the recommended lube is plain old white lithium grease ! Does the shoebox use polyurethane o-rings? I know a lot of folks swear by polyurethane o-rings even though they are a lot more expensive.Any thoughts on the dynamic applications or the Shoebox?Oh, and an engineer I know and trust says that Parker Super O-ring Lube (from an industrial supplier) is the best he has seen for dynamic applications. I haven't tried it yet.Lloyd