I stand corrected: cap on threads not screwed in. Bike on wheels and balanced upright. There were some dipstick "malfunctions" over the years some were too short? Anyways If you are using a lot of oil and there aren't puddles it's burning it. You could get a leak down tester, NOT THE HARBOR FRIGHT POS, but no reason really, the engine has to come out and you will need to do a top overhaul. Once you are there the problems will most likely be visible. and you will measure and replace what's needed anyways. The only question is do you want to keep riding it "As is" for the summer or do it now.