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Help-Where's my Oil Going?

88K views 144 replies 50 participants last post by  NJTB04 
#1 ·
Hope someone can help, searched the threads but didn't see my issue. Bought a used (Certified) 06 Denali. To be honest we have had it in three times in 3 months, mostly little crap.

I haven't changed the oil yet, but checked it before a trip over Christmas and needed to add a quart. Just thought the dealer never topped off so didn't think much about it. Checked at the end of the trip, needed another 1/2 quart. And just added another 1/2 quart today.

Call me crazy but I shouldn't have to be adding 2 quarts between oil changes with 34K on it. No leaks that I can find underneith and nothing on the garage floor. Not seeing any smoke or signs of burning oil. Engine is running fine, and not throwing any codes.

We had a 04 Envoy with the I6 and over 90K when I traded it in. Never once did I add oil btwn oil changes. Getting a little concerned we my have a problem child.

Any ideas?:confused:
 
#2 ·
I would say you definitely have a problem somewhere. As you probably already know - oil can only disappear in one of two way. Either the engine can burn it by the oil getting past the rings and/or valves, or it is leaking somewhere.

Sometimes an engine CAN burn oil and it will not be enough that you can see it while you are driving.

Something you could try is - change the oil and use a different brand. I have heard (but never experienced) that occasionally a different brand of oil will cause it to use oil. I'm not sure I buy it - but that's what I've heard, and like I said I've never seen that happen in any of my vehicles.

You can try complaining to the dealership, but they are probably going to tell you nothing is wrong.

I usually go about 7K - 9K miles between changes and have never had to add oil - with the exception of when the engine was new I had to add one quart.
 
#4 ·
I'd bet that this level of oil consumption is considered normal by GM.

To fix this you need a lot of engine work. Cost would no doubt be thousands of dollars, and the problem might not be fixed. Even if you use synthetic oil at $5 per quart, $1000 will buy 200 quarts of oil.

You don't say in your post, but just exactly how much oil is your truck using? Are you using synthetic oil? If so stop using synthetic. Also, changing brands might help this issue as well.

In any case, I don't think GM will do anything for you.

Try the things listed above. Keep us posted.

-- Dan Meyer :coffee
 
#6 ·
Could be leaking around valve cover gasket? Mine has started using quite a bit.. I just add it.. until I can pinpoint whre eit's coming from. I don't think it's blow by (ring failure) because it does not smoke at all.. on startup or any other time. I have noticed a little seepage near the CPS or whatever it's called.
 
#8 ·
I've put about 2 quarts in for about 2-3000 miles. I have not changed since I bought, but assumed that the dealer used regular 5W30 not syn. Owners Manual calls for regular. Mostly after highway driving. Figured I'd call the dealer in the am and see what they say. Really disappointed however, have had a bunch of crap with this one. And I would would have thought a Denali would be better built then a base Envoy XL. Had no problems with that.
 
#9 ·
check the POSTIVE CRANK VENTILATION SYSTEM PCV its maybe the engine not cooled by air i,m mean from inside this valve could make the oil boiling if its defected or check the engine oil cooler if you have my biggest idea is your oil is over temp
 
#11 ·
First off this is a 5.3 not the I6, second, I would assume if the oil is over heating the engine would be as well? That does not seem to be a problem.

I did call the dealer today. I will take it in and they want to change the oil and put a dye in then check every 1000 miles, however he did say they have a bulletin that says the motor can use up to two quarts between oil changes and still be normal. That seems like a lot to me and from this forum I don't see anyone else saying they have this issue, particularly on a motor with 34K on it.

I am certainly not an expert, would like to know if anyone else has experianced this on a 5.3.
 
#14 ·
Read my post very carefully. I said it doesn't have a PCV VALVE! Yes there is a hose, but not a serviceable valve like many cars have.

This is also mentioned in the link I posted to the other thread.

What you had before in a V6 4.3 engine really doesn't have any bearing with what our engines have. Completely different animals!
 
#16 ·
purchased on 06 denali as well, had it for a month now and have not changed the oil. I checked recently and it is just above the lower XXX marks on the dip stick.. I would figure that the dealer would change the oil and fill to the top of the XXX marks..

did you find out what is going on with your Denali and what did the dealer do to fix? or if they even fixed??
 
#17 ·
I bought a used 5.3L TB in December with 51k. I now have about 55k on it, meaning I have driven 4000 miles or so. The oil had been changed by the dealer, and it was full when I picked it up.

I have now put two quarts into it. The oil life monitor says 29%.

Previously I had an I6 03 Envoy, and went 10k without putting in a quart. So, I"m spoiled, as are you.

BUT, until I had an I6, I would have thought that one quart every 2000 miles was perfectly acceptable. That is about what I get in my 3.8L Bonneville.

My tentative conclusion is that a quart every 2k is "normal" for the 5.3L.

My other conclusion is that if I am replacing 40% of my oil before the oil life monitor says change the oil, then I can go 40% longer before I change my oil. I'll reset the monitor but not change the oil, and then change it when I get down to 60%, by which time I'm sure I'll have added yet another quart.

Just my thinking.
 
#18 ·
My other conclusion is that if I am replacing 40% of my oil before the oil life monitor says change the oil, then I can go 40% longer before I change my oil. I'll reset the monitor but not change the oil, and then change it when I get down to 60%, by which time I'm sure I'll have added yet another quart.

Just my thinking.
I would rethink your thoughts! :D

Going on your theory, you would almost never have to change the oil!:crazy:

I would change your oil when the OLM states to and call it a day. Oil changes are relatively cheap - engines are not.
 
#19 ·
According to the service manual for the 5.3, "Excessive oil consumption, not due to leaks, is the use of 1 qt or more of engine oil within 2,000 miles."

Preliminary causes listed are:
-External oil leaks
-Incorrect oil level or improper reading of the stick
-Improper oil viscosity
-Continuous high speed driving and/or severe usage
-Crankcase ventilation system restrictions or malfunctioning components
-Worn valve guides / stems
-Piston rings broken, worn, or not seated properly
-Piston and rings improperly installed or not fitted to the cylinder bore.

For the 4.2, it's 1 qt within 1,500 miles. Same causes.
 
#20 ·
since I have yet to change it since I got it from the dealer since driving it approx 3k miles. The DIC states I have 70+% I don't think that is right. If that is the case I can drive 9k before It reaches 10% oil life left. I am hoping that it was just reset on accident prior to me getting the car.
 
#21 ·
since I have yet to change it since I got it from the dealer since driving it approx 3k miles. The DIC states I have 70+% I don't think that is right. If that is the case I can drive 9k before It reaches 10% oil life left. I am hoping that it was just reset on accident prior to me getting the car.
Probably not. The OLM is very accurate and takes into account many things, not just mileage. Some of the I6 engines will go about 12K miles before the OLM states to change it.

Too many people are hung up on 3K mile oil changes. The is from the 60's. A lot has changed since then.
 
#28 ·
Well I'm fairly new at this job (I've been working at a GM dealership for a month now), so I'm not 100% certain, but that information is directly from the GM Service website that we (GM Techs) have to work by.

That particular PI (Preliminary Information) was just recently posted, and the fact that it's considered Preliminary Information leads me to believe that there have been enough cases of the same problem to warrant a bullitin and possibly could become a recognized campaign (A known defect that GM will pay to correct, similar to a recall).

Again I'm new at working for GM, so this is my best guess.
Today is my day off, so tomorrow I'll ask someone who knows better how PI's and service bullitins work.
 
#33 ·
Here is a helpful link that supports my thinking. Especially the quote about oil not wearing out.

http://www.blackstone-labs.com/news..._Diesel_Newsletter03_31_2008&utm_medium=email

In terms of the "salts" point, aren't they solids, and wouldn't they be captured by the filter?

As for the fuel in the oil not boiling off point, two comments. First, today's engines burn so efficiently that there is rarely if ever fuel in the oil. Second, gasoline does evaporate quickly, so even if it doesn't boil off, it will evaporate away and be burned by the engine through the PCV system. Yes, there may be some additives that remain, but nobody has shown (me) that they have a deleterious effect upon motor oil in a crankcase.

Finally, as for the assumption that oil "lost" or "burned" doesn't take its share of impurities with it, I beg to differ. Let's take leaking oil, as that is the easiest case. Leaking is the same as draining in my book. If I drained a quart of hot oil, or sucked a quart out the dipstick tube, it would contain its share of the impurities in suspension. So on a full engine (6 quarts I now see from the Owner's Handbook, not the 5 quarts I assumed--you can tell I haven't had to change oil yet), draining one quart will take 1/6 of the contaminents etc. with it. I submit the same is true if the oil goes down the valve guides or through the PCV system.

Just my thinking. YMMV.
 
#34 ·
Finally, as for the assumption that oil "lost" or "burned" doesn't take its share of impurities with it, I beg to differ. Let's take leaking oil, as that is the easiest case. Leaking is the same as draining in my book. If I drained a quart of hot oil, or sucked a quart out the dipstick tube, it would contain its share of the impurities in suspension. So on a full engine (6 quarts I now see from the Owner's Handbook, not the 5 quarts I assumed--you can tell I haven't had to change oil yet), draining one quart will take 1/6 of the contaminents etc. with it. I submit the same is true if the oil goes down the valve guides or through the PCV system.

Just my thinking. YMMV.
Problem is - if your "thinking" is right, and the lost oil DOES take some impurities with it, what about the other 5 - 6 quarts in the engine (depending on the engine).

Personally I think this is really a moot point. I think you just like to "discuss". As I said before, if you want to do it to your truck be my guest.
But I certainly would NOT recommend it.

Plus like I said before - you can theorize all you want - but I've seen a LOT of engines tore down. Most of these were oil burners were people were adding oil constantly - some as much as every 200 - 300 miles. They had the same theory as you - since I'm adding so much oil I don't need to change it.
Let's just say it was not a pretty site.
 
#39 ·
I didn't see this thread. My 5.3 Denali puffed blue smoke yesterday, first time seen. Oil level is below cross hatched area on dipstick. Have 17% left on DIC but doing oil change anyway. My tail pipe also is very blackened. To the dealer on Monday with that PIP info bulliton to check PVC drain areas. Well at least I'm not the only one with the problem. If there is a fix out there for exssevive oil consumption I hope my warranty covers it. Any other 5.3 owners with this issue?
 
#40 ·
i have never had this problem with my tb but my mom bought her 03-04 envoy forgot what year it was, but since day 1 she has had this problem. she bought it off the showroom floor. 2 miles on it. she changes the oil every 3000 miles on the dot. she is the only driver and she does the same exact driving route and sometimes the oil level is right up where it should be and others its 1-2 quarts low. i dont get it. im glad mine isnt like that
 
#45 ·
HELLO i have a 2006 trailblazer 5.3l engine.it consumes about 1 1/2 to 2 quarts of oil every 3,000 miles.it has 47,000 miles on it and is still under gm extended warranty.gm is doing an oil consupmtion test on it now.which means they change the oil and you bring it back to them when it needs more oil and they will keep up with the amount of oil it consumes.the kicker here is that they all say there is an acceptable level of consumption, however none of them knows what it is.i have have taken it to three dealerships and talked to two others.in my mind this is absolutely unacceptable.my 1988 c1500 with 250,000 miles didnt use oil like this.i also noticed that when the dealer ship changed my oil and started the "test" they accidentally overfilled it by a quart or so. By the time i caught it and got it back to them it was barely showing overfull and they denied it was ever overfull.the thing that really gets me here is that if they say this is acceptable then what good is the cute little oil life moniter.i will run completely out of oil before it tells me to change it.thanks for any ideas or for just letting me vent about it.
 
#46 ·
Hthe thing that really gets me here is that if they say this is acceptable then what good is the cute little oil life moniter.i will run completely out of oil before it tells me to change it.thanks for any ideas or for just letting me vent about it.

I see what you are saying. At the rate you are going you could put almost all new oil in there before the light tells you to change it.
Since the Oil Life Monitor works off a computer algorithm, it measures engine rpms, temps, load, stuff like that. But it doesn't know what kind of oil you have in there, how much new oil is in the mix, or even IF there is any oil in there.

I agree this amount of oil usage seems excessive. But this has always been a problem with car makers. I've heard some of them say 1 quart in 1,000 miles is "normal".
My I6 doesn't use any oil in between changes, which is about 7 - 8,000 miles.
 
#51 · (Edited)
Duhhhh.. I didn't read that far into it... My bad.

Attached are a few pics of where I have now determined mine is leaking.. These were taken when changing oil yesterday... You can see the frame rail in a couple of them..

I'm no mechanic, so I'm not sure what part this is coming from. It looks like where the half shaft mates to the transmission just above the oil pan? Correct me if I'm wrong.







 
#52 ·
That's not engine oil, that's gear oil. That is your front differential. From your pictures, the left front axle seal is definately leaking but the pinion seal may be leaking as well. I would try and get that fixed soon, looks like it's been leaking for a while and you don't want that front diff to run out of fluid.
 
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