On my diesel Mercedes, I run 12,000 miles between oil changes. Yes thats right, twelve thousand. I do change the filter and top the oil off every 3,000, and at 6,000 and when I change it, I send a sample in to Blackstone Labs for a UOA or "Used Oil Analysis". Theres two reasons I do this.
- I want to know whats going on with my car. I'm approaching 280,000 miles quickly and its nice to know whats going on inside. Kind of like bloodwork.
- I use Synthetic Oil, which is costlier but one of the key benefits I like is better protection and extended drain intervals (or so they claim)
- Extended Drain intervals means less impact on the environment, even if you do recycle the oil.
So the last UOA report I just got in, shows that wear materials are high, and potassium is high. I spoke with a guy at the lab and he explained that just changing the filter isn't going to remove the amount of wear materials (iron copper etc) from the oil, and most certainly not coolant. Now if I had a bypass filter on this car, then I would be fine for thousands of miles more, but how far are we going to take this on a car fast approaching 300,000 miles?
Anyway, heres a link to the report.
I think the plan here is to change the oil at 5,000 this time and send a sample in again to see whats going on. The odd thing is, I'm not losing any coolant. Go figure.