Why is my oil black after only several hundred miles? Its an 88 TII, still running the OMP. the previous owner claims it another owner before him ran synthetic oil in it. My other 7's oil doesnt start to turn black till after 2000+ miles. Any ideas?

 

Old synthetic oil was probably still in the oiler cooler so its tainting your new oil and making it look black. Try completely draining the oil from the engine, filter, and coller and then replace with new oil. You can use compressed air on the cooler to empty it out. It may take a few times to completely flush it out.

 

Color doesn't matter. You can't tell how much of the lubricating properties are still left in the oil based on color. Modern tests are showing that oil doesn't begin to lose it's lubricating properties until after 10k miles (most new cars have their recommended oil change interval at 10k now as well because of these studies).

However, with a rotary, you deal with blow-by which will cause some fuel dillution. So, I don't recommend waiting 10k on a rotary to change the oil, but just ignore the color.

 

If you wait till 10K to change your oil, you won't have a lot left to change and will probably have a damaged engine!

Rotaries eat oil as part of the combustion mixture to lubricate the rotors since they aren't bathed in oil like in a piston engine. That means they use, by design some of the oil as they run. That means about 1/2 quart every 1000 miles or so.

 

Im sure after 13k+ posts Mahjik has figured this out by now

The previous owner had it for 6 months before me, so its been through several oil changes at least 5 or 6. When i first got the car, I did two oil changes in a week to 'flush' out the system too.

 

[sarcasm]boohoo black oil, what are you racist now[/sarcasm]

 

I never pay attention to the number of posts, only the content of the messages.

Did you change the oil filter and drain the cooler ? If so maybe your hoses or other engine soft parts (seals) are deteriorating and making the oil look black. Here's another thought, is the engine running real hot, maybe that oil is actually getting burnt, but I would suspect other problems as well if that was the case.

The color of the oil is important, its one of the first clues that something "not good" is happening in the engine.

 

The ONLY time that is true, is if the oil is some other color besides black. If your oil comes out green, then yes there might be a problem.

 

(google for the heck of it)

Myth #2

If the oil turns dark or black quickly, it's no good.
You can tell the condition of oil by the look, smell or color of it.
Dirty (black) motor oil means the oil is breaking down.

Fact
A common misconception is that high quality motor oil should come out of an engine looking clean at the time of an oil change. Nothing could be further from the truth. If the oil is doing its job of cleaning the engine, then it should be dirty when it is drained. Motor oil will start looking dirty a short time after it is put to use. In the case of diesel engines, the oil will look dirty within a few hours of operation. These are signs that the motor oil is doing its job of keeping soot, dirt, and other combustion contaminants in suspension to be carried to the filter or removed from the crankcase when the oil is changed.

 

definitely not trying to be anything close to a smart ***... cause i know very little, but theoretically you are saying that by the oil being black, the filter is not doing its job??

 

Think about it this way: If you mix some powder Koolaid with water and then run it through a filter, will it come out looking just like water again after the filter? Nope. But if there are only unmixed Koolaid, it will catch those particles.

There is only so much a filter can do.

 

i would assume because the oil filters are rated to a certain value of micrometers for the particles it can catch...

 

EXCESSIVE BLOW-BY


-Ted

 

What is more important is the additive package's ability to handle contaminants.

I haven't heard of any cars with a 10k servive interval. It is usually 5k or 7500 for "normal" service, 3k for "severe" service. You should read the definition of "severe" service, then tell me where a car does not fall into that category. The problem is contaminants.

Some cars *do* have oil change computers, in that there is an algorithm based on temperatures and trip lengths and so on. In many cases these will not call for an oil change for well after 10k... in cars that see mostly highway use. Short trip/cold start use is just perfect for loading up the additive package with contaminants and is why you should change your oil based on *time*, not mileage.

Two additional points. Most automakers lease cars now, and their only concern is minimizing costs to the consumer during the lease period. After that, they can fribble off.

Secondly, there's at least one major automaker that is recommending 2500 mile oil changes. Am fairly sure but not entirely certain that this is now mandatory for them to honor the warranty. Sludge is bad, especially in timing chain tensioners...

 

These two cars for starters:

http://mahjik.homestead.com/files/Ho.../Garage_01.jpg

My M3 and my wife's Audi A4.

False, my M3 was at 13k last time. Right now, it's calculated at 14,7xx miles. However, it does hold more oil than most cars.

 

What years are they? When I get back to work on the 2nd I will look up the scheduled service intervals.

Wait, how can you say "false" when you're repeating what I said, that cars with calculators often go over 10k given lenient conditions?

And yes, it does help when a system holds 7 or 8 quarts, and when the car has a water/oil cooler to GET THAT OIL WARMED UP. The problem is when people who drive differently and/or have more normal 3 1/2-4 1/2 quart systems try to apply the same service interval. Then you get sludge and failing tensioners and other goodies.

My favorite are the Rover Group's aluminum V8s (the Buick engines). Every one I've had to have off (right around 70-100k when the owner gets fed up with the timing cover leak) had a solid quart of jelly in the bottom of the pan. "But i changed the oil every 7500 like the manual said!"



(Personally, I can't stretch my Nissan longer than 3500 before the timing chain starts reminding me that I'm slacking off in my duties)

 

I'll attach the service book page. The M3 is a '02, the A4 is a '05 but the '01 it replaced was the same way.

That't my mistake as I read that as a negative with the word "not" in there.



Simple fact is that you can't tell the condition of the oil straight from the color (as the original question). There are other factors but oil CAN retain lubriating properties well beyond 10k.

Does that mean you can run 10k road racing miles on the same oil? No (and likely you'll have burnt so much off before then you'll have a new tank of oil). Use a little common sense when reading. I never said you can run 10k miles of any type of driving and be just fine.

 

Actually, I'd rather race on the same oil for 10k (assuming a proper cooling system) before doing 10k worth of cold-starts and incomplete warmup cycles.

Reference Nissan again. When the temps get below 40 degrees (a third or so of the year), my car barely comes up to thermostat opening temp by the time my 15 minute drive to work (half throttle-bolted-to-floor highway, half city) is over. The one RX-7 was almost as bad for warmup, poor thing would require full choke in the winter for pretty much the whole drive in (all city in that case).

The lady I got the Nissan from maybe drove it a mile, two miles at a time, tops. 47k in 15 years, oil change every six months. No wonder it clatters like a Diesel, it's worn out long before its time.

I'm still curious about the service intervals. Our maintenance guides come straight from the factory, and I don't recall any newer BMW/Audi product having a schedule longer than 7500. Usually 5k or so for severe service, which most climates and driving styles get lumped into. It wouldn't be the first time that two different sets of information from the same source didn't jibe with each other.

As I said, can't wait to get back to work and get the scoop.

The problem is, people DON'T use common sense. They see a report that says "the oil maintains its lubricating qualities past 10k" and they don't look into it any more than that, then they wonder why their engine sounds like hell after only 100k after acids in the oil have had their way with the bearings, or the HLA's are plugged, or the timing chain slacks off enough to jump time and wreak havoc. The lubricating qualities are a small factor in what makes oil work.

The oil color thing always gets me, too. "Why is my oil dirty? You just changed it!" "It's *working*..." I'm honestly paranoid about oil that looks the same coming out as going in, the combustion byproducts (raw fuel, water) have to be going *somewhere*.

Not to mention, fresh oil can, to a degree, clean up deposits in the engine, darkening the additives in the process.

 

Well, I don't consider a 15+ year old Nissan in the class of "most newer cars" when referring to oil service intervals.

Unless you work at an Audi service shop, it won't reallly matter. That scan is exactly what Audi is putting out to the customers and exactly what their dealerships (at least the one in my area) is following.

Not that I can't do my own in between their intervals, but that is their "normal" schedule maintenance intervals.

 

Thank you, but come check out my car and see why it isnt eating up any oil as "designed".

 

meh.. i dont wait to 3k miles usually right around 2-2.5k . "black" oil is normal for rotaries because they o burn some oil ,as someone posted way before me LOL