Curious...Oil darkens quick, any problems?

[FrozenPilot]

In the two years I've owned my Saturn ('95 SL1) I've notice that the oil has a tendency to darken rather fast.. faster than any other cars that have been in the family garage. When I speak of fast, I mean in about 500 miles of driving, it looks like its halfway between the new golden color and used blackened oil.

The car has 68k, I used dino 5w-30 when I bought it at 45k, then switched to Mobil1 5w-30 and 10w-30 around 57k. I had a piston ring service done at 53k by Saturn, and have been thinking of going about 6.5k on the latest fill of M1 10w-30, but I'm a little leery. I'm sure a UOA would be good, but I haven't yet justified spending $20 to find out, you know, college student budget. (BTW, I'm running M1 to avoid any more piston ring sticking, common on Saturns)

So, without doing a UOA, i was wondering what the oil experts here thought about this.

 

[TR3-2001SE]

I am not a expert but I have noticed that an engine that runs rich and has fuel problems will make the oil very black quickly. Also it seems a excellent filter like a Mobil 1 or Pureone can keep the oil looking cleaner longer. A UOA will show if you are getting fuel in your oil. Other than that try a better filter. My toyota cressida with 250,000 the oil stays clean looking for about 2000 miles. I use the Pureone filter and regular dino oil. My miata with mobil 1 the oil turns brown immediately and never changes much over 5000 miles.

 

[Dr. T]

In my experience the darkening is coming from the oil burning inside your engine...hence it is charring.

You will notice diminished darkeing with a thicker oil and/or an A3 one. ie. instead of the M-1 5/10-30...use 0-40 or 15-50.

 

[MolaKule]

A rich fuel mixture and/or excessive blowby can quickly turn an oil black.

 

[G-MAN]

quote:

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Originally posted by Dr. T:
In my experience the darkening is coming from the oil burning inside your engine...hence it is charring.

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[TallPaul]

I wonder if the oil just happens to be cleaning out a dirty engine. If so, it should run cleaner after a few oil change cycles.

I once had a '77 F100 300 I6 that I bought new. That truck always turned the oil black in short order. Because of that I always ran 2000 mile oil change intervals.

 

[haley10]

Castrol GTX gets dark real quick. Syntec stays golden longer. M1 can get pretty dark in a couple thousand in my experience. The old Havoline stayed golden.

Only a uoa will tell. I don't think coloration means a lot. Smell and feel are better indicators, if you can't do a uoa.

It's not unusual for some oils to turn dark quickly in any engine. Dark GTX and Mobil 1 is normal.

 

[Propflux01]

excessive blow by will cause this. Even if the engine doesn't 'use' alot.

 

[FrozenPilot]

I hope i don't have blow-by, Saturn replaced the piston rings in January 2003! I'll check the feel of the oil but I'm guessing a UOA will be my best bet, just to be sure.

Just did a smell/feel test. Smells like used oil to me, feels like oil. Checked the odometer... 261 miles on this oil. I've never seen it get dark this fast, but we did have a week of -30F starts where the engine did flood some. At least the oil read full on the dipstick, right where I filled it at. Guess I shouldn't worry til I get a UOA done and get the results back.

[ February 24, 2004, 03:36 PM: Message edited by: FrozenPilot ]

 

[jthorner]

Two things I would check out straight away:

1) Running mixture. An engine running rich will blacken oil quickly. Is your fuel economy about where it was when the car had 20,000 miles on it?

2) Do a compression test. Given the history of an early need for new rings on your car I would be concerned. If you get one or more cylinders with low compression readings it is highly probable that there is excessive blow by.

If #2 is found, a slightly thicker oil might help hide some of the symptoms for a while. One of the thicker High Mileage vehicle oils or Long-Life/Delo/Delvac 15W-40 might be helpful in the warm season.

John

 

[FrozenPilot]

quote:

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1) Running mixture. An engine running rich will blacken oil quickly. Is your fuel economy about where it was when the car had 20,000 miles on it?

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Fuel mileage went down about 3mpg highway after the ring replacement. But oil color did the same prior to and after it. O2 sensor has been replaced and according to a scan tool the readings it gives are correct. Even reading the plugs themselves shows a proper burn.

quote:

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2) Do a compression test. Given the history of an early need for new rings on your car I would be concerned. If you get one or more cylinders with low compression readings it is highly probable that there is excessive blow by.

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This is where it gets expensive. S-series Saturns have oil consumption problems. At 53k I took the car in to have them look at it. According to them, they replaced the rings to a tune of $1300! We got them down to $480 after talking to the general manager. After all, I bought the car from them in that condition. I would assume they would check things like compression, but I could be wrong. This is the point where I would just live with it until I get rid of her. I am planning on going with Rotella T Synthetic at the next change simply because I feel this weight would be better and save me some money in the process.

 

[FrozenPilot]

quote:

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Originally posted by TallPaul:
I wonder if the oil just happens to be cleaning out a dirty engine. If so, it should run cleaner after a few oil change cycles.

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I thought that was the case too, but after 30k miles of ownership, and running MMO in the crank for 1k miles, I thought it would be ok. My fuel economy went down about 3mpg highway and a little more around town, but the oil was doing the same darkening beforehand.

I've run a PureONE filter once, but didn't notice any change. I run SuperTech filters now, just because they're slightly cheaper and better than Fram.

Thinking back, I did get a remark from a lube tech about how dark my oil was. I ran Mobil Drive Clean for 2,900miles. He said, "Thats some black oil!"

Maybe I'll spring for a UOA when the change is due this summer. Even if it does find fuel, after the maintenance I've done already, I think it would be too expensive to fix, considering I'm only keeping the car for another 4 years til I turn 25!

 

[TR3-2001SE]

[A rich fuel mixture and/or excessive blowby can quickly turn an oil black. ] by MolaKule


If this is the case why does my Toyota which is an oil burner or was an oil burner ie 1 quart every 500 miles but the oil did not turn black till around 2000 miles????? I guess the 20w-50 castrol gtx must burn very clean?

[ February 24, 2004, 12:50 PM: Message edited by: TR3-2001SE ]