I think it's a silly test myself. What does it tell you? The engine has been driven around for 30 years. There's no precision measurement to be taken, no stats to compute, just "Oh, I guess it didn't roll off the assembly line yesterday after all."

I mean, I guess if you found one that didn't have that then you'd know it might be worth the fat roll of hundreds. That's about it though.

-Rog

That, and the other end of the spectrum. If the cap flies off followed by plumes of oil spray, you have a ring or piston slop issue.