randomly losing oil 6.2

[drivereye]

loosing oil on 2020 sierra 6.2.

Oil let came on. Topped up and dropped off at dealers. They found no leaks and set me up to do a consumption report.

After 3200km the dipstick did not budge and the dealer said there appears to be no issue. Next fillup I found i had dropped another litre.

So I took pictures of every oil check at every fill up. Same pattern no oil loss until 4000km then i suddenly lose a litre.

Not towing, no changes in driving patterns.

Black tailpipes, no leaking, drives fine, noisy idle when sitting in driveway.

Sending pictures to service manager monday.

Any thoughts? experiences?

 

Tom

 

[Grumpy Bear]

A few things come to mind. 

 

1.) Oil level new is almost always over full and near impossible to read on these wire dipsticks so it's using from day one but doesn't register such until sometime later. The fix for this is leave a quart out on the next change and then after started and the system warm and engine off add that quart about 3 ounces (1/10 liter) at a time until it just reaches the full mark and use that as your reference. Remember it has to be level, warm, and at least 15 minutes drain time between fill and read for a consistent check. 

 

2.) GDI motor dilute the oil more than any other fuel delivery type. 4 or 5% sometimes if it doesn't get long enough runs. While that will actually raise the level the dilution thins the oil enough to move about 1 SAE grade. Thus is uses more over time as it becomes more dilute. UAO's and helpful in figuring this out. Even 2% in an 8 quart system is 5 ounces. (0.15 liters). 

 

3.) Not full to start with. Shops filling from quarts will leave up to 2 ounces per bottle in the bottle they go so fast. Just had this on my truck and it accounted for almost 3/10 liter (9.5 ounces). I always ask for the bottles.

 

4.) Oil usage is based more on fuel burnt than on miles driven. 'Normal' is roughly .03 to .05% of the fuel burnt. Some are tighter but when it starts getting past that larger number something is up. Problem is. GM is unwilling to do anything about it until it reaches more than a quart per 2K miles which is a hideous level of usage. Keep track of the fuel used. Gas ticket totals for the OCI. It won't help you win a case but it will educate you on what your trucks 'normal' is. 

 

That will keep you busy awhile    

[redwngr]

For accurate level checks, do them in the morning before the first start, rather than at fill-ups.

 

 

[diyer2]

Personal choice but I have always checked my oil level after sitting over night. 

If it was me I would change oil brands and upgrade the oil filter and see what happens. 

How often are you doing oil and filter changes? If you are using a semi-synthetic or full synthetic oil, dealer or a common brand oil I wouldn't go over 5K miles.

Edited March 21, 2021 by diyer2

[Grumpy Bear]

Ever notice there is a cold mark and a hot mark on an ATF dipstick? A cold mark on your radiator overflow tank? Ever notice the distance between hot and cold on the ATF? Same idea applies to motor oil. The only difficult parts of doing the check hot after a fill up is 'time', 15 minutes. Everyone is in a hurry. Finding a level pad at a pump. 

 

Don't believe me. Try it. Do your cold in the morning check then go drive for a hour, park it for 15 minutes in the same place and check it again. The dirtier the oil gets the more unreliable the cold check becomes. It 'wets' the stick differently. Which was never an issue with flat blade sticks but these bullet types 'wick'. Believe your eyes, not my words. 

[RWTJR]

11 hours ago, redwngr said:

For accurate level checks, do them in the morning before the first start, rather than at fill-ups.

 

 

I agree and so does the 2020 manual (pg.336):

 

Follow these guidelines:
To get an accurate reading, park
the vehicle on level ground.
Check the engine oil level after
the engine has been off for at
least two hours. Checking the
engine oil level on steep grades
or too soon after engine shutoff
can result in incorrect readings.
Accuracy improves when
checking a cold engine prior to
starting. Remove the dipstick
and check the level. (emphasis added)

 

Good way to insure "the engine has been off for at least two hours" and the oil is checked "prior to starting" is to check it before for the first drive/start of the day.

 

JMHO

No expertise implied or expressed

[drivereye]

I should clarify. I am recording dipstick levels and odometer for diagnostic purposes because i am losing large amounts of oil at inconsistent times.

Same drive, same gas station, same timing (fill, clean windows, check oil). Yes i know it is not 15 minutes or two hours but it is consistent. I park on an incline so overnight would be inaccurate (but still consistent, so perhaps ill try that as well)

The only significant variable would be the outside weather, but the engine temp would minimize that enough at least for these purposes.

 

Guys,  I get the nuances of oil quality, dirt, temp, timing effecting dipstick readings, but we are talking about full, full, full, full, litre down. Top up or change oil and do it again.

 

Tom

 

[newdude]

2 hours ago, drivereye said:

I should clarify. I am recording dipstick levels and odometer for diagnostic purposes because i am losing large amounts of oil at inconsistent times.

Same drive, same gas station, same timing (fill, clean windows, check oil). Yes i know it is not 15 minutes or two hours but it is consistent. I park on an incline so overnight would be inaccurate (but still consistent, so perhaps ill try that as well)

The only significant variable would be the outside weather, but the engine temp would minimize that enough at least for these purposes.

 

Guys,  I get the nuances of oil quality, dirt, temp, timing effecting dipstick readings, but we are talking about full, full, full, full, litre down. Top up or change oil and do it again.

 

Tom

 

 

 

Its not consistent then.  Consistent would be checking it per GM procedure to ensure proper drain time back to the sump, not 5 minutes after the gas tank is filled.  

[drivereye]

22 minutes ago, newdude said:

 

 

Its not consistent then.  Consistent would be checking it per GM procedure to ensure proper drain time back to the sump, not 5 minutes after the gas tank is filled.  

I agree that for the next round I will be as precise as possible on monitoring the levels to rule out any unexpected variables.

I have a hard time understanding how if I have a slow consistent burning of oil, that the dipstick will not indicate anything before 4000km checking at gas station. But again, I can verify this by checking oil in the mornings.

What i am curious about is what could possibly cause an oil loss in a 500km period but not other 500km periods. If driving habits and routes stay generally the same?

 

 

[Booger T]

4 hours ago, RWTJR said:

I agree and so does the 2020 manual (pg.336):

 

Follow these guidelines:
To get an accurate reading, park
the vehicle on level ground.
Check the engine oil level after
the engine has been off for at
least two hours. Checking the
engine oil level on steep grades
or too soon after engine shutoff
can result in incorrect readings.
Accuracy improves when
checking a cold engine prior to
starting. Remove the dipstick
and check the level. (emphasis added)

 

Good way to insure "the engine has been off for at least two hours" and the oil is checked "prior to starting" is to check it before for the first drive/start of the day.

 

JMHO

No expertise implied or expressed

Also need to wipe dipstick off when you first pull it and then re insert and use that reading. For some reason it seems to read fuller if you don't do that.

[RWTJR]

43 minutes ago, drivereye said:

What i am curious about is what could possibly cause an oil loss in a 500km period but not other 500km periods. If driving habits and routes stay generally the same?

 

I think this is what has prompted all the discussion about consistency and protocol adherence in measurement because this defies logic. I am not stating or implying you aren't losing/burning oil at an accelerated rate because you could be. I am just saying without following the measurement protocol it's impossible to rule out a measurement error.

 

So the question is, are you actually burning/losing oil in an illogical, erratic fashion or does it just appear so due to how you're checking your oil?

 

If the truck is actually burning/losing oil in the manner described, I'd get rid of it.

 

Please let us know what you discover.

 

JMHO

No expertise implied or expressed

[Brad M]

Similar issue with my 2020 Denali.  Oil consumption test from dealer indicated almost 2 quart consumption in 1700 or so miles.  Was around 16,000 miles on truck.  Dealer Tore down motor, ash on one piston and cylinder walls scored.  Motor replaced and then ran into a few electrical gremlins.  
 

3 different trips to dealer to deal with electrical stuff.  Appeared to be some chafing on wiring harness either from engine swap or another TSB - sorry don’t have number.   Now have about 1000 miles on since last issue.  Hoping all resolved now.  
 

Good luck driver eye.  Keep us informed on what happens with yours.  

[drivereye]

update

after several months of oil consumption test by the dealer, they acknowledged excessive oil consumption. The loss they recorded was inconsistent, but always excessive. I was going through 5 litres between oil changes. They called today and said the cylinder wall was scored. They ordered a new block under warranty. I am curious if the valves would be compromised in any way from the excess oil burning.

 

[Grumpy Bear]

13 hours ago, drivereye said:

update

after several months of oil consumption test by the dealer, they acknowledged excessive oil consumption. The loss they recorded was inconsistent, but always excessive. I was going through 5 litres between oil changes. They called today and said the cylinder wall was scored. They ordered a new block under warranty. I am curious if the valves would be compromised in any way from the excess oil burning.

 

 

No.

 

How many miles/km do/did you have on this motor? How many when it started using?

 

 

 

 

Edited September 2, 2021 by Grumpy Bear

[drivereye]

Just over 50000 km now

I was not monitoring the oil consumption at first, it was around 40000 when the oil light first came on and I started paying attention.