[eliminator]

I disagree. The color of the oil has nothing to do with whether or not it needs to be changed. For example, in heavy diesel engines the oil looks like TAR almost immediately after it's changed, and then the oil is used for 25,000 miles or more. On the other hand, a lot of newer cars have clear, clean looking oil at 5000 miles, but an oil change may be past due. The oil's appearance means nothing. The things to be concerned about are: 1) moisture accumulation, caused by short trips and not letting the motor warm up. This will turn the oil to sludge in short order. Generally not a problem if you get on the highway for a few miles once in a while. 2) Overheating of the oil, which will cause it to break down. This isn't an issue for our cars because of the oil cooler. 3) Loss of additive package (detergents, mostly). This is normal for any oil and will occur over time, regardless of what oil and filter you use. It's kind of like when you wash dishes - you need to change the water once in a while because the soap gets "used up".

DCX recommends 5000 miles between oil changes (with standard oil), and they are being very CONSERVATIVE because they have to warranty the motor. Volkswagon and others also recommend 5000 mile intervals for their turbo motors. 5000 is not unusual. They wouldn't recommend doing something that would damage the motor. 5000 is very SAFE for normal use.

Oil companies and mechanics LOVE to preach about 3000 mile oil changes, so they can make more money.

I'm going to send a sample of my 5000 mile oil to a lab in a few weeks, and I'll let you all know what I find out.