>I found that with the Castrol Syntec, the valves did the ol' "tap tap" >routine, but when I switched to Mobil 1 15W50, they didn't. I'll stick >to the Mobil 1. Same here on the Castrol. Let's just poll a few of the Big Boost Boys: Myself 4 cars Mobil 1, Scott (PDQSHIP) 2 cars, Ned Ritchie Lot's of cars......... NJTH Later! Eric Fletcher '87 5KCSTQIA2RSR2B STEADI RIC@aol.com