Does the Upper Cylinder Lubricant (by Lucas for example) when added to the crankcase oil really do any good? Or is just a waste of money?

If you believe whats written on the containers they come in they are wonderful, kind of like buying insurance for your engine. But the real question when you add the dollars up that you spend on them, have they saved you an equal amount of dollars in gas savings or premature engine wear

If you want to extend the life of you engine use one of two things, synthetic oil or slick 50. Everything else is a waste of money.

It's really hard to say. Upper cylinder lubricant in the fuel costs about 4 cents a gallon. If you use cut-rate gas it probably would reduce engine deposits. If you used gas such as Shell you get the additives with the gas. So you would break even on cost. I like Marvel Mystery Oil. I add it to fuel that is 10% alcohol because it is a drier form of gas. Do I get any more mpg? Hard to say. 4 cents a gallon is pretty cheap insurance. Maybe it doesn't it doesn't help, but it sure doesn't hurt either.