M1 5W-40 T&SUV, 8k miles, 1996 Audi A4 2.8 V6

[moribundman]

As you can see this Audi 2.8 V6 12 valve motor is using some oil these days. One quart every 1k miles is generally not unusual for this type engine, and I'm "okay" with the 0.5 qt/1k mile oil consumption. Oil consumption is largely dependent on how I drive.

This oil was in the vehicle for almost exactly one year, and although I have done 10k mile OCIs since the car hit 50k miles, I was concerned about this not VW502 approved Mobil oil and wanted to have it tested.

As some of you may know, I used M1 0W-40 for only a few thousand miles because the engine was awfully loud at idle when hot. It's nice and quiet with the 5W-40.

My driving style is sporty and I redline the motor several times a day. However, I haven't been driving much during the past year, and I drive now more city than I used to. Half of those 8k miles are probably city driving, the rest is coastal highway and some freeway.

Please keep in mind that I added 4 quarts of oil during the past 8k miles. The report states I did not change the oil, but I did it anyway after seeing how dark the sample looked.

I paid for the Dyson analysis, but haven't heard from Terry yet. Maybe he can add a comment here.

Please, anybody feel free to comment, expecially because the art of UOA interpretation eludes me.

PS: Audi motors tend to run rich, by the way.

PPS: In case the image exceeds the allowed limits, please click the link to see the report: http://tinypic.com/1sjc0o

[ February 23, 2005, 07:26 PM: Message edited by: moribundman ]

 

[buster]

Everything looks great but I have to ask why even change the oil if your going through that much oil per change? Is this type of consumption normal for this engine? Seems like a lot.

 

[moribundman]

buster, many Audi 2.8 12 valve motors need upward of 0.5 quarts per 1k miles. Audi allows up to 1l/1000k km (~1 qt/700mi) If I drive the car lame I can cut that consumption in half. Until the car hit 70k miles I didn't need more than 1/3 qt per 10k miles! Between 70k and 120k miles I have had so many oil leak issues (which I have completely eliminated during the past 11k miles) that I could not tell oil consumption from oil loss.

Why did I change the oil? I've never seen any oil come that dark out of my motor, and I did not mind paying $35 for oil and filter. I was considering changing just the filter, but the belly pan has to come off to get to it, so I figured I'd just drain the oil.

I'm worried about valve stem seals and rings (low tension) on this motor. That's the two things that commonly go bad before anything else.

I am wondering whether or not the high phosphorus and zinc level in this oil may be a problem for my cats.

 

[Palut]

Even if you double the wear numbers to account for all the make up oil, they look pretty good, especially with the spirited driving you describe.

M1 5W-40 is supposed to have a lot of detergent power. Since it came out dark, maybe that means its doing a little cleaning. Oil consumption can tend to increase while cleaning goes on, can it not?

 

[buster]

quote:

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I am wondering whether or not the high phosphorus and zinc level in this oil may be a problem for my cats.

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Thats a good question. I agree with Palut though in that SUV = D1 which will do a good job cleaning so this is why the oil could be dark.

 

[Jay]

If you only used 1/3 qt per 10,000 miles (up to 70,000 total miles), then 1/2 qt per 1000 miles is not "normal" consumption.

It looks like the ring or valve stem seal failures you fear caught up with you many miles ago.

 

[moribundman]

Palut, oil consumption was 0.75 quarts during the first 1000 miles after switching to M1 5W-40. Consumption tapred off and 0.5 qt/2k miles is the average for the 8k mi OCI.


Jay, the oil with which I had practically no consumption was Syntec 5W-50. Niether dealer nor independent shop believed the 1/3 qt oil per 10k mile figure! Syntec 5W-50 seems to curb consumption in many engines, though. As I said, that particular motor is known to burn oil, and my consumption figures are in line. I do however suspect that my valve guide seals have been less than perfect for over 40k miles. I used to see puffs of blue smoke when engine vacuum would change. This has however not been happening in over 20 k miles. I'm more worried about the rings than the valve stem seals. My driving style isn't exactly good for long ring life.

 

[Cutehumor]

have you tried auto-rx in this engine?

 

[moribundman]

quote:

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have you tried auto-rx in this engine?

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No, and I won't. A friend used ARX as prescribed in the same engine with zero change in terms of oil color, sludge deposists, or compression result. It must be an Audi/ARX thing.

This is how dirty my engine was at 122k miles:
http://tinypic.com/x95ed

I suppose the extra detergents in the 5W-40 cleaned some crud out somewhere, or the oil is simply darker, because it's darker to begin with and/or because it holds particles better in suspension.

 

[moribundman]

Would anybody like to comment on the TBN? How much further do you reckon I could have safely gone?


PS: I forgot to mention, the oil filter was an Audi LongLife filter.

 

[1sttruck]

Mobil states that the Truck & SUV is for gasoline as well as diesel engines. If it killed catalytic converters one would assume that it wouldn't be recommended. Besides, some diesels have cats and they all still use HDEO.

 

[moribundman]

quote:

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Mobil states that the Truck & SUV is for gasoline as well as diesel engines. If it killed catalytic converters one would assume that it wouldn't be recommended. Besides, some diesels have cats and they all still use HDEO.

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Although my reasoning differs from yours, I tend to believe that the additives in the 5W-40 are not a critical issue. The proper VW oil spec allows a 1.5% sulfated ash limit, which is below the 1.5% limit of M1 5W-40. Audi allows oil consumption of up to 1 qt/700 miles. I'm sure VW/Audi figures oil consumption into the equation.

 

[moribundman]

Here are a couple of my own thoughts:


I really can't comment much on the wear numbers, but even if I multiply them by 1.75 they seem fine. Looks like Blackstone doesn't have any other 2.8 12v Audi motors in their database for comparison.

I'm surprised fuel was
The vicosity seems to have held up nicely. Looks like this oil did not shear or thicken, right?

Silicon seems low, considering that I had the intake and the filter out a few times during the past year. I also live by the beach, and sand is everywhere. I also had the intake manifold out. Looks like I didn't contaminate anything.

Calcium, magnesium and phosphorus levels seem a bit higher compared to other M1 5W-40 UOAs. How come? The residual moly should be from the previous M1 0W-40 fill.

Not sure about TBN, but looks like I could have easily gone 10-12k miles!

I'm pretty happy with this result, I guess, but I'd still like to hear what some other people have to say.

 

[TooSlick]

Delvac 1 has excellent dispersancy - based on these results, I'd feel comfortable going to a 12,000 mile change interval.

TS

 

[moribundman]

Something else I meant to ask: if the rings were bad or even shot, would that show in the UOA?

 

[TooSlick]

Morbundman,

Yes, it would show up as increased solids, depleted TBN and high oxidation/nitration.

You probably could benefit in this case by replacing the valve stem seals ....I think the rings are just fine.

TS

 

[jason07-1zzfe]

If Syntec 5w-50 helps with consumption why aren't you using that?

 

[Geoff]

On the valve stem seals, there may be a better compound used in the replacement part or in an aftermarket product. I know Land Rover changed to neoprene for instance. Some types of oils are more friendly than others to the seal compounds.

 

[moribundman]

quote:

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Morib, the 'read' is in your email. Kinda sounds like the "fix" is in .. [Roll Eyes]

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Terry, you don't have to roll your eyes. I'm game. I really enjoyed your very professional analysis and look forward to some more testing. Hopefully, I can improve things with your help.

quote:

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The oil signature that we see here is more consistant with Delvac than the advertized TSUV and I suspect bottling has used both variations interchangeably.

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I bought the first batch of M1 5W-40 when it showed up early last year. I suppose Mobil has fiddled with the formula since.


Geoff, they have indeed valve stem seals made from a better material (green Viton, I think) available. In case of a repair, I will upgrade.

Jason, my issue with Castrol isn't with the product itself, but with its "full synthetic" labeling. Finding out about Castrol's rhetoric when it comes to "synthetic" doesn't make me want to give Castrol any more money.

TooSlick, I hope you're right about the rings. I'll see if I can find anyone who will perform a compression and leakdown test.

 

[Terry]

Morib, the 'read' is in your email. Kinda sounds like the "fix" is in ..

The oil signature that we see here is more consistant with Delvac than the advertized TSUV and I suspect bottling has used both variations interchangeably.

I look forward to your responses and tightening things up a bit. Chemistry can correct for the lower tension oil control rings and that may be a player here too.

For proprietary reasons I will leave my public comments there and await your feedback.


Sincerely, Terry