i just happened to think of another? i have an 03 merc, with the 4.6. having gone from a 92 caprice to the merc, i wasn't familier with the newer clearances and oil requirements. went to change it the first time and the book said 5W30......NOT IN MY LIFE! aint no engine gonna last long with 5 weight base stock......so i went to 10W30, and immediately got a "tick" upon start up, which went away very shortly. studied up on the subject and went back to the 5W-30, and never a tick, since? the 10 weight was too thick.....