I used to think Amsoil was a superior product bc they claimed 25k mile drains and Mobil didn't. While I do think Amsoil is more suited for long drains, I think Mobil does the right thing by not recommending anything other the what the manual says. Most cars give a severe oil change interval and normal interval. Normal driving conditions today are around 5-7,500k miles. Personally, based on everything I've read, I think it is smart to follow these limits. Unless conditions are very good, it's just too risky to extend drains withouth analysis. Too many variables and driving conditions to just use a standard number. IMO.
Not too mention we live in a time where everyone wants to sue someone for as much $$ as they can. So you really have to cover you @ss today more then ever.
[ February 22, 2003, 02:19 PM: Message edited by: buster ]