Have had my oil changed recently, in my '90 300E, with a 10-10 filter (old style) and 10-40 dino, and have noticed it now takes about three seconds for the pressure to jump to 3 bar at start-up. I have gathered on the forums that the oil filters include a check valve to keep the filter full, but is there also an "O" ring inside the filter housing to further prevent oil leakdown?? This delay has me worried, as start-up lube is the most critical.

Also, is it coincidental that the engine misses badly until the pressure builds up?? I cannot see the connection between crank-case pressure and the rest of the miriad variables that create the successful start-up!! The symptom is much more noticeable when the car is warm and since the oil change. Any ideas? TIA

steve