[metroschultz]

I used oil analysis @ my last fleet shop.
We installed a petcock on the side of the filter housing in an un-used gallery port.
Draw sample with engine running. Shut down and change filters. Send off sample and wait for results.
Approx 2 weeks for test result returns.

The testing center will send you the results and a pamphlet explaining the numbers.
% raw fuel
% coolant
% soot
Etc.
They should also include an explanation of which numbers need to be what.
I don't remember any of the tech stuff right now, except;
Any coolant is a bad thing. They will suggest you change oil, drive 1k miles and re-test. If you still have coolant in the oil it is time for a re-man. If there is a lot of coolant in the oil you might not make it to 1k miles.
I am using the "white rag test"
Drive home from work, do not shut down engine.
Pull oil dipstick and wipe on a clean white rag.
Carefully inspect resulting stain.
look for metal (looks like fish scales in sunlight)
look for dirt
look close for water ( will run the fibers of the rag swiftly)
check overall color (color will change with age, but tar black is bad, Milkshake brown is really bad, darker brown is not necessarily bad)
oil should still be at least translucent. Maybe not perfectly clear though.
re-install dipstick and remove again. Draw through you fingers. Rub fingers together and feel consistency, check for "stickiness" and granulate material (sandy feeling)
Wipe fingers with rag.
I used this method when I would commute 250 miles to work.
I started doing oil changes @~3500 miles in the old Rabbit.
After a few months I was stretching my OCs to 10,000 miles.
The oil actually still seemed good, I couldn't force myself to go farther on an oil change. we didn't have synth back in the 80s.
I would be tempted to go up to 15,000 with synth.
Check you owners manual though. Please don't void your warranty by NOT doing regular OCs.
I repair cars and trucks for a living and have sen the damage non oil changing can do. I also understand not throwing away perfectly good oil just because it isn't 'pretty' anymore.
I am currently changing oil in the Avalon ~5,000 miles.That number is getting larger as I do more OCs. I think the last owner went to BillyBob Lube and Hot Dog Stand too infrequently.
I haven't changed oil in the Geo since last spring.(it is changing itself on a regular basis)
Good luck with the Oil Analysis Guys.
I hope they help you.
Anyways that's my personal oil analysis system.
It works for me and I haven't lost and engine yet. Due to oil failure.
I may have lost a couple due to driver error.
The NAPA store by me offers Oil Analysis. IIRC it is ~ $10 us.
Abba goo dai.
S.