[...]   
   RW> I don't. When the 'change oil' light comes on in my Silverado, the    
   RW> vehicle has only 3000 miles on it after being reset from a previous    
   RW> oil change. I use Mobile One (synthetic) in my vehicles and the oil    
   RW> maker's recomended change is at 5000, 7500 at the latest. My dad    
   RW> (an auto mechanic) told me about the 3000 mile rule when I was a    
   RW> kid. The reason he stated was that dirty oil tends to sludge an    
   RW> engine quite fast, especially in Y-block Fords of the era. I once    
   RW> saw the results of what he was talking about in a 55 Chevy that    
   RW> never had the oil changed; it was sludged so badly that you    
   RW> couldn't find the push-rods in the lifter valley, nor the rocker    
   RW> arms in the heads. That one belonged to my high school girl-friend    
   RW> at the time, who got the car from her father as a hand-me-down. It    
   RW> was almost 5 years old then...   
       
   I'd already seen an engine in that condition which is why I don't mind   
   changing the oil sooner than it should be.  Now I also have to care for my   
   daughter's '95 Suburban and '99 Yukon.  I couldn't get over the smooth   
   acceleration and the comfortable ride of them both.  Vastly different than the   
   '84 Chevy PU I had, which drove and rode like a truck.   
       
       
   Regards,   
       
   Roger   
      
   ... To every rule there is an exception, and vice versa.   
   --- D'Bridge 3.55   
    * Origin: NCS BBS (1:3828/7)