Black OIl

My Toyota and Honda both have I4 engines and both use 0W20 synthetic oil. The Toyota oil says clean looking for many thousands of miles. The Honda turns black pretty quickly (1000 miles). Both cars run fine and show no evidence of problems. What gives? Does color mean anything?

Oil color generally means that the oil is doing what it’s supposed to do…clean the engine by way of detergents. If you keep the oil changed on a regular basis…you should have no problems. Some engines are just sootier than other engines so that probably explains why the Toyota oil looks cleaner longer.

The oil not only washes out the wear surfaces as it lubricates them, but it also washes down the cylinder walls. Some engines produce more micron-level contaminants that don’t filter out than others, including such things as blowby, which is the process of combustion chamber gasses blowing past the rings, which get captured in the oil.

If the Honda is older that the Toyota, more wear is in the parts and more blowby can be expected.
If the Honda has a turbocharger, additional heat is experienced by the oil as it cools and lubricates the bearings between the exhaust side of the turbocharger and the intake side of the turbocharger.

In any event, what you describe is perfectly normal. If it makes you feel more comfortable, you can always change the Honda oil more frequently. I probably would. But, then, I’ve been known to do unnecessary things to my car.

My Honda (at 107,000 miles) stays clean nearly the entire change interval. Do one short change interval, say 1500 miles just to see if you can clean up any excess junk built up over the years in the engine and see how long it stays clean. If it stays clean longer, go back to your regular interval, if not, follow @the same mountainbike 's advice, shorten the interval 1000 miles or so. It just shows the oil is working as intended as @missleman says.

As others have said, this is normal. It is the detergent in the oil doing its job. My dad experienced the same thing in a 1954 Buick he bought from a friend in 1955. Dad switched from the detergent oil that was being used to MacMillan high detergent. The oil turned black in 1000 miles. He changed the oil again and it stayed clean for 2000 miles. 2000 miles was the normal period between oil changes back then.

All of my Hondas (4) have turned the oil dark alarmingly fast. I learned to ignore it.

The oil in my wife’s 2012 Mazda3 turns dark sooner than the oil in my 2007 Toyota, which remains amber colored like maple syrup right up till the 5000 mile change out time. Neither car uses oil.

The Honda is producing excess soot. I would not think twice, were the Honda a diesel, but a petrol engine should not soot up so quickly. There must be an issue that needs to be addressed. DO the short change cycle with a high detergent oil then see what the next cycle is like.

My '03 Civic EX with 160K miles - the oil stays clean for a long time after an oil change up to and beyond 5,000 miles it still looks only slight brown and clear. I’d suspect a problem if my oil got dark fast. Is the dark color a change from when the motor was new?

Concerned About Your Oil? Call Blackstone Labs And They’ll Send You A Bottle In Which To Enclose A Sample And Instructions On How To Sample And Send It Back (With A Reasonable Charge).

I did this with a used car I purchased and was happy with the prompt, complete analysis I received. These folks are “user friendly” and there’s a place for comments on your submission form. Ask them what you asked us and they’ll probably give you some useful information.

It would be interesting to send samples from both of the vehicles that you reference.


What are the model year and mileage of each car? Have they both always used synthetic oil? The reason I ask is b/c if you didn’t use synthetic oil on the Honda at first, then switched to synthetic, that could explain what you are seeing. That would be normal, the synthetic would be cleaning out the passages that the normal oil didn’t clean while it was in use.