I found this "learning" recently posted on the Synthetic Oil Life Study site quite interesting. Seems counter intuitive.
Engine wear actually decreases as oil ages. This has also been substantiated in testing conducted by Ford Motor Co. and ConocoPhillips, and reported in SAE Technical Paper 2003-01-3119. What this means is that compulsive oil changers are actually causing more engine wear than the people who let their engine's oil get some age on it.
quote:I've read the summary twice. Still don't fully understand why. Gotta be more than just "top off" oil?
While the wear metals all accumulated steadily over the course of the test, the highest concentrations of accumulation per mile occurred in the first 3,000 miles of the test! From the 3,000-mile mark all the way to 18,000 miles, only lead showed an increase in per-mile wear beyond 3,000 miles. Yet even with an increased wear rate, lead wore the least in terms of absolute wear. For iron and copper, the longer the oil remained in service, the lower the wear rate got. In case it isn't obvious yet, this means that the most wear occurs in the first 3,000 miles.