oil problem....

[Rico]

I noticed that after the last oil change this past thursday and
365 miles later the oil is super black!

I have a bone stock 2.4T with the original MFI.
I run an oil cooler in front with factory lines back
to the engine.

The motor and MFI are running fantastic, so I
cant figure out why the oil is turning black so
quickly.

Has this happened to anyone else??

[Chuck Miller]

I guess the part of the info we're not getting is... Is this the same type and brand of oil you used before that didn't get 'black' after that many miles ... or is this a new oil you're trying ????

There are a few oils on the market that turn black as soon as they get up to temp the first time.... especially the synthetics

Cheers,

[rick2]

Once the front cooler stat opened the old dirty oil mixed with the new??? Did you drain the oil out of the engine as well, not just the tank? Hope any of this helps.
Rick

[Gearbox]

I assume you are using some form of dino oil and not synthetic, and that during your oil chnage you did drain the sump on the engine. My experience is that it will turn black almost imediately as the oil washes and mixes with the remainants of the old oil still clining on the internal components and what you couldn't get out of the oil cooler and lines. The black comes from the slight blow back into the case causing carbon to build up even if the engine is sound. I took an engine apart with only 30,000 miles and found shovel fulls of sluge in the pan due to the orignal owner never having changed the oil. I also just recently drianed a quart or two on my 71S after I realized I over filled the sump. And even after two 10 minute starts on new oil, what poured out was very black. Strangely, the dip stick oil was discolored, but not as opaque, but it was darkened. If you are really concerned you can do a leak down check and see if you have anything out of the ordinary. Then listen to see if it's the valves or rings. But I wouldn't worry about it, especially if you have some miles on the motor, I say it's normal. You didn't see any metal shavings did you? LOL, Good luck Allan

[sithot]

I think this has been around but it's good reading.

http://www.lnengineering.com/oil.html

In the old Beemer MC engines some of us have gone "old school" and started using non-detergent oil in our roller bearing motors (Pre-70 /2 and earlier) as there are no filters other than "sludge traps"/slingers. A non-detergent is better as there is no other filtration system and keeping dirt in suspension is exactly what the factory didn't want so out with the detergent oil. FWIW, Morris Lubricants make a nice product.

Tom

[72targa]

Rico:

If the oil turned black that quickly, you have successfully added a modern engine oil with a high dispersant level (one of the additives) that is pulling all of the sludge on the inside of your engine into solution in the oil. It all comes out when you drain the oil (as desired). Go ahead and change it out with the same oil some time soon and recognize that you're giving your engine a good cleaning. With all due respect to other advisors, whether or not the oil is synthetic or petroleum ("dino") is not the issue. Hope this reduces your stress level!

PS - The link above mentions comparing oils based primarily on zinc and phosphorous levels. These happen to be easy to measure metals in engine oil. Unfortunately, they primarily indicate the level of zinc dithiophosphate which primarily functions as an anti-wear agent (and as a minor anti-oxidant) in engine oil. You're better off choosing a viscosity and looking for an API SM oil. Hope this helps.

[Gearbox]

No offense taken Rico, was just attempting to establish a level playing field in which to discuss as per the two previous posts. Didn't know the chemistry of the different oils, but sithot's article was very informative. I was just going by personal experience. Bottom line was we arrived at the same conclusion, not much to worry about. So which is a better oil? The one that washes and suspends the contaminents or the one that doesn't? Have to re-read that article again, best regards Allan

[Rico]

Thanks for the replies.

The oil I'm using is Castrol GTX 20-50.
I drained the oil tank and the engine sump.
New filter also.

I talked to a mechanic down the block from
my office (knows little about early 911's) and
he seems to think its unburnt fuel mixing
with the oil causing the black discoloration.

It still doesnt make sense to me....

Remember, I only have driven 360 miles
since the oil change.

[sithot]

A rich running engine can turn oil black in a hurry. Even faster if she's prone to blow-by from being "loose".
Also, MFI is notorious for running rich. As they system ages it wouldn't be hard to imagine that someone before you has tinkered with it to make the car run smoother.
The old cars were also hard on guides or let's rephrase that by saying the guides weren't up to the job because they weren't hard! Porsches were prone to valve guide wear and to do them at 40,000 wasn't uncommon back in the "old" days. By 60,000 and they were all gone.
One thing to consider: If you adjust your valves and they are noisy within a short period your guides are definitely worn.

There is a procedure that falls into the bag of "old tricks" where you can check them. I'm not going into the oily details because it is involved and the first test is usually good enough to know. (This involves attempting to rock the valve stems to check for wear.)

A long time ago valve jobs were not an uncommon occurrence and we smiled and took our medicine. The medicine cost around $1,200 back then.
And, a nickel bag was only a nickel!

Good luck,

Tom