Oil gets black after 200 mi.

History-1994 XJ w/4.0 and auto- Bought new and has had Mobil 1 since the third oil change- changed religeosly between 3-4K mi-car has 70k on it now.

At about 55k mi's I started noticing that the new oil was getting darker than normal between changes. Now when I check the oil after about 200 mi's after a change I see that it is almost completly black. The intake system doesn't have any leaks and I change the air filter at least once a year. There are no leaks and it doesn't get that dusty around here.

Is there a way to flush the engine doing a couple of changes at the 200 mi. interval w/some cheap oil and filters? Has anybody done this? Should I just switch to Valvoline or some other dino juice? This car has had mostly city mi's and short trips for the first 56K of it's life.

This is my 3rd 4.0 litre, and neither of the other one's has done this. Both had more miles but in a much shorter time frame. Both of the other one's had the same oil and change schedule. I really want to drive this car (no rust, dents, scratches,rips or fades) untill the wheel's fall off and this has me slightly concerned.

You might want to pay the money and have an oil analysis done. They can tell you if something is going wrong. I talked an Army Oil Analysis Program and he said you get get commerical analysis starting at $8 and running up to $275.

I am not sure where you'd have one done but sure someone on here would tell you where to have it done.

The test will give you an idea if anything is going on, a good place to start.

I second Martin, but if you want to "flush" it out you can put a quart of tranny fluid in the oil and run it for 100 miles or so and then change the oil, Or they actually make engine flush for doing the same thing. It has been my experience the tranny fluid works just as well and is cheaper.

Call me crazy but I've always drained the oil from the engine and while the plug is still out dumped two quarts of oil straight through the engine to help get some of the dirty oil out. I also have dumped the oil, refilled, run the engine and dumped the fresh oil occaisionally. The oil coming out looks just as clean as the new oil going in... Probably overkill but I like clean oil!

As for the oil analysis, I've never done one on my car by on the aircaft I fly we always do it as part of the Mx program. Here's a link if you want to try it...

http://www.youroil.net/oil_sample_kit_single_.html