Steve's thoughts are right on. I recall when the blue Mercedes gasket was mentioned in one of the early e-mail lists. I bought them then and they did save a lot of grief for lots of guys. Then the vent hole thing is spot on as well. My 1992 cap has the two holes in the top of the cap welded shut. These were there for venting the gas tanks of the Mercedes cars. With our set-up if not sealed they will neutralize the pressure provided by the Pitot vents and allow spilling in all the attitudes mentioned including light turbulence with full tanks. I think I found some of the blue gaskets on ebay and ordered a couple as mine are the typical black replacements. I will report when they get here if they are actually the ones mentioned.