I wonder how he knows the oil is dirty? Does he do an analysis too find out how many insolubles are in the oil? Or does he judge it by color? Some engines will turn the oil black before 1,000 miles. Why does he say 3,000 when every engine treats oil differently? Some engines will still have clear oil at 3,000 miles - does he change these too.
As stated before, most mechanics are just that, MECHANICS. The may do a very good job of diagnosing problems and fixing them, but they know very little about lubricants and how they work. Do they do harm by changing the engine oil at 3,000 miles, no - at least to the engine. I have a locally reputable mechanic work on my truck - he uses Harley Davidson's Syn3 in his bike because it says Harley, Harley says it's better than conventional oils, and he can afford over $8 per quart. I use what I, and many other consider to be a better synthetic and cheaper because, with the help of many people here, I have educated myself about lubrication. Once again, this guy is a great mechanic, but doesn't know a thing about lubrications.
Don't forget about the filter, isn't the idea of a filter to clean the dirty oil? If you have a bypass filter, you should be able to go many miles beyond 3,000 without an oil change.
Most owners manuals now recommend 5k - 7.5k OCI's. A few even go up to 15k miles OCI's. Do you think the manufacturer would recommend this if it was going to damage the vehicle? 5,000 miles isn't really considered and extended OCI anymore.
[ November 29, 2003, 05:11 PM: Message edited by: medic ]