dirty oil, and quick

Change the oil and filter according to the owner's manual.

The oil is dirty because the detergent is doing its job.

Jeff

Uh...arent I doing that now?

My theory is that the difference is due to differences in the way the oil pans are mounted on the engines.

The 4Runner is a conventional design, with the oil pan mounted on the bottom of the engine. Cylinder blowby comes down directly into the oil pan, aided by the downward motion of the pistons. The oil picks up particulates in the gas. If one or both compression rings are worn or sticking, the oil will get dirtier more quickly before the PCV valve vents the blowby into the intake.

The Previa's engine is canted over on its side and the oil pan is mounted on the side of the engine. Blowby hits the raised side of the oil pan instead of being pushed directly into the oil, and the PCV valve has a chance to vent the gas before the particulates get picked up by the oil.

I dont remember ever having this problem on my 86 4runner.

Without seeing the OP's oil first hand, it is difficult to determine if his

4Runner's oil gets dirtier than normal. Another possibility is that the old oil is not draining completely for some reason, like the angle of the oil pan when draining.

if I had a digital camer I'd post a picture. You'll just have to trust me that in 30 years of driving and over 400,000 miles of it on my 3 Toyotas (2 4runners and a Previa) I've never seen oil get so dirty so quick.

I suspect that the oil is not draining completely, and some dirty oil is mixing with the new oil, making it appear dirty. Otherwise, if the something from the engine were making the oil dirty, it would quickly take on the consistency of tar.

That seems like a logical idea, but I change the oil the same way in the same place as I used to change my 86 4runner's oil. Its a mystery I guess, but since I want to sell it I'd like to solve it. Maybe two changes in a row will flush out the filth.

The Previa and the 4Runner have oil pans that are shaped differently, so positioning both vehicles at the same angle may have different results.

Rather than 2 changes in a row, try this: After you have drained the oil in the 4Runner, change the oil filter, and then pour a quart or two of oil into the engine and then drain without starting the engine. This may flush out the dirty oil in the bottom of the pan that did not drain out. Look at how the oil pan is shaped to make sure no oil will pool in it when it is jacked up.

On Apr 16, 11:28 pm, "Ray O" spake

That seems like a logical idea, but I change the oil the same way in the same place as I used to change my 86 4runner's oil. Its a mystery I guess, but since I want to sell it I'd like to solve it. Maybe two changes in a row will flush out the filth.