Grime on Dipstick - Low Mileage Vortec Motor

[Vortec_4300]

Hi All -

I have a new Chevy Silverado work truck (4300 V6) with approximately 8,000 miles on it. I purchased the truck on May 13th of this year with 12 miles on it, so that gives you some idea of the amount of highway mileage that I am accumulating in fairly short order.

I changed from the factory fill to Pennzoil 5W30 and a Mobil 1-101 oil filter at 1500 miles, and again at 5000 miles.

I just checked the oil and noticed a dark gray grimey substance on the dipstick - not too much or terribly noticeable, but it is definitely there. Also, in the 3,000 miles since my last OCI, I have apparently burned approximately 1/5 of a quart of oil.

Can anyone tell me what this grimey stuff may be? Am I extending the OCI out too far? I was planning on having a Dyson Analysis at 10,000 miles, but I will happily change the oil earlier if necessary.

Thanks in advance!

 

[kenw]

check the coolant, your oil may be in there.

let's hope not.

 

[Drew99GT]

Your colent may be in the oil. Gm has major issues with internally leaking intake manifold gaskets. Check the oil fill cap for condensed moisture/grey goo. Check the coolent reservior for low coolent.

 

[Vortec_4300]

Thanks for the response - I'll check the overflow tank and under the oil fill cap as per your recommendations.

If there were coolant getting into the oil, wouldn't my oil level be increasing? As I mentioned, it seems to have gone down a little over the past 3,000 miles.

 

[JHZR2]

yep, check the coolant, I had a very slight leak in my 98 4.3

Ive run pennzoil fr long periods of time, the engine is very easy on the oil, and so unless youre really stressing the engine for work, I cant imagine it is breaking down the oil like that.

JMH

 

[Drew99GT]

Since you do so much highway driving, if there actually is coolent getting in the oil, it's probably being burned off quickly and that's why your not seeing the level rise. Plus, many times the leak is tiny. I can't imagine this problem showing up so early in a 4.3L's life

It's under warrenty, no? Bring it in if it is.

 

[Vortec_4300]

I've checked the coolant level, and it seems OK (but as Dreww99GT indicated, it could be a very small leak.)

I've just changed the oil at 9,170 miles and sent a sample to Blackstone for a Dyson Analysis. I'll post the results.

Thanks for the insight - if there's a coolant leak, I'll be on it quickly, thanks to this Board.

 

[Dave H]

Personally, I'd guess the dark gray grimey stuff is because your engine is just getting broke in. After the parts get worn in to each other, that should go away.
Good call on the oil analysis. That's the best way to figure out exactly what is going on. But I wouldn't be surprised if some of your wear metals show high. This gets back to the break-in period. Several of them may be needed before your wear metals level out, and then you'll be able to spot a trend more accurately. Of course, fuel or coolant in your oil should be investigated because that would not be the norm.
With those few miles, I'd be concerned if I was burning 1/2 quart of oil. But from my experience, a 1/2 quart can easily be explained away by inconsistencies in checking the oil level. Even a slightly unlevel parking surface or a slightly cooler engine can skew the accuracy. Try checking the oil in the same exact conditions each time if possible (same parking spot, time after engine was running,etc). When I check mine at a gas station, I don't use that check as a basis for adding oil. It is more just to confirm that I have oil or am not ridiculously low. I check mine at home with the car in the same spot and engine cold (I know it says to check hot, but I know where it should be when cold and all the oil is in the pan). This gives me the most accurate, consistent measurement.
Just re-read your post and saw you said 1/5th quart in 3000 miles. That is approx 6 oz, which I would say is within the margin of error for checking with a dipstick. Some people would even say that is perfectly acceptable if burned over 3000 miles. It may be for some vehicles. On my two Nissans, that would be excessive. On my two old GM's, it would be normal. I'd just keep a mental note and see how it goes.

Dave

 

[Vortec_4300]

quote:

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Originally posted by Dave H:
Personally, I'd guess the dark gray grimey stuff is because your engine is just getting broke in. After the parts get worn in to each other, that should go away.
Good call on the oil analysis. That's the best way to figure out exactly what is going on. But I wouldn't be surprised if some of your wear metals show high. This gets back to the break-in period. Several of them may be needed before your wear metals level out, and then you'll be able to spot a trend more accurately. Of course, fuel or coolant in your oil should be investigated because that would not be the norm.
With those few miles, I'd be concerned if I was burning 1/2 quart of oil. But from my experience, a 1/2 quart can easily be explained away by inconsistencies in checking the oil level. Even a slightly unlevel parking surface or a slightly cooler engine can skew the accuracy. Try checking the oil in the same exact conditions each time if possible (same parking spot, time after engine was running,etc). When I check mine at a gas station, I don't use that check as a basis for adding oil. It is more just to confirm that I have oil or am not ridiculously low. I check mine at home with the car in the same spot and engine cold (I know it says to check hot, but I know where it should be when cold and all the oil is in the pan). This gives me the most accurate, consistent measurement.
Just re-read your post and saw you said 1/5th quart in 3000 miles. That is approx 6 oz, which I would say is within the margin of error for checking with a dipstick. Some people would even say that is perfectly acceptable if burned over 3000 miles. It may be for some vehicles. On my two Nissans, that would be excessive. On my two old GM's, it would be normal. I'd just keep a mental note and see how it goes.

Dave

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Thanks for the feedback - I've actually been thinking the same thing about the gray grime and the slightly low oil level.

When the oil was changed, it was quite dark, and I know that this engine couldn't have become that dirty in such a short amount of mileage (particularly given the fact that almost 99% of my mileage has been highway mileage with the engine turning between 1500 and 2000 RPM.) I'm hoping that break-in is the reason for the oil being as dark as it was, so I'm hoping to hear the Dyson results soon.

As far as checking the oil, you're absolutely right - I wasn't consistent in the methodology for checking (although I did try and ensure that the truck was on level ground.) I am going to check the oil very frequently during the next 3000 miles, and use the same consistent method for checking. If the engine is burning oil, I'll soon know that as well.

 

[Vortec_4300]

UPDATE

I just posted my first UOA in that section, and the report from Blackstone Labs indicated that there was no coolant in the oil at all.

I am going to wait for some of the more knowlegeable types on this Board to opine about the results that I've posted, but maybe Dave H was correct and I am simply seeing normal break-in residue?