Well after all the talk about the engines not being ready for synthetic until 8k+ . I called SVT and one of the engineers confirmed this for me. He told me " ONLY MINERAL BASED OIL UNTIL,AT LEAST 8K! & ONLY 5W-20" So I changed it again w/ a new Motorcraft 820S & 6qts of 5W-20 and she is back to normal! Hope this helps. Brian

 

blownlightning, glad to here the good news. I have a 00L. Iam sure I have to use 5w30 . I will call SVT Monday to see if I can use 5w20. Maybe a thinner oil will quite up the engine. Bob.

 

Bob my 00 used 5W20 Stated in the manual and on the filler cap.Although I always used Valvoline synthetic 10W30 And never had a problem! Hope the 5-20 works for you! Brian

 

FYI
have only seen 5w20 in symi synthetic and fully syn, I personally have used mobil 10w-30 full synthetic from my 95 lightning new
to my 01 lightning never had a problem 1!!
I work for ford and it has been my experince they promote there own product i e 5w20 motorcraft

 

also
5w20 will not quite down the motor, it was intended to be a fuel saver (emmisions crap!)

 

Blownlightning, happy to hear that things worked out.

 

usahooters, Thanx buddy! I don't think it was the lighter weight oil that quieted the noise because it was always a bit mechanical sounding, as is any performance engine! I personally think it was the mineral based vr.s synthetic at short milage.At around 8k I am trying the synthetic again! I'll keep you all posted. Brian