Im may not get a clear answer to this but I will shoot anyway. Situation my car and the truck gets the oildchange in the garage at about the same time but one thing I noticed is like now on my car the oil has about 2800 miles on it and the color is still kinda light brown not even close to dark yet and part of its miles are from playing around town and a few passes on the track and the blower uses the engine oil too the oil thats always been it is motorcraft syn blend. Now on the truck it has about 2600 miles on it and the oil is almost on the very dark side and the truck is used by the wife to nd from work no play in it and hasnt been to the track since 2009 so no track use on the oil and its fairly stock besides a catback the oil use is mobile1 synthetic. Question is why does the oil breakdown on the mustang seem to be alot slower than the breakdown of the oil on the truck when the car is driven hard alot more often than the truck both using quality oils. Any info will help im just curious. Car 03 mustang Gt v1 s trim, Truck 06 Trailblazer SS catback.