disappointing oil change
Thread Starter
Le Mans Master
Joined: Oct 2008
Posts: 8,894
Likes: 981
From: Whitby Ont.
disappointing oil change
changed the oil in my Z51 today, have changed it a few times and i thought maybe it would improve, but apparently not. i change it, comes out pretty black, put the new oil in, run it for a bit to make sure no filter leaks and etc, check it, right on the mark, but already discoloured, not very happy, is it because with the oil cooler it is not all drained out and some of the dirty oil is still in there ? can t figure it out. i changed the oil on my 2006 Sierra with 147k km, and drove it all day and still looks like it came out of the jug, and will remain like that for at least a month, but the Vette, i don t get it. any thoughts ?
Melting Slicks
Joined: Aug 2000
Posts: 2,327
Likes: 44
From: Sacramento CA
Blackstone Labs
Next time you change oil, send a sample to Blackstone Labs. They will give you a report on how your oil is doing. (You have to request a sample kit first on the Net.)
My 13 GS Looked pretty bad, but after sending a sample in and getting a report, all is well.
The new oils with the better detergents get dark pretty quick..
My 13 GS Looked pretty bad, but after sending a sample in and getting a report, all is well.
The new oils with the better detergents get dark pretty quick..
Melting Slicks
Joined: Mar 2009
Posts: 2,321
Likes: 71
What oil are you using and what's the heat range you run it the hottest flashpoint in Mobil 1 if I remember is 325.....so if your running it 220 230 all the time then the oil is breaking down quicker......Get a test done.
Tech Contributor
Joined: Oct 1999
Posts: 41,058
Likes: 9,820
From: Charlotte, NC (formerly Endicott, NY)
Are you putting Synthetic Detergent oil in the Sierra? My 03 Tahoe with 100K miles keeps the new oil color longer than my C6Z does. However, I use detergent dyno oil in the Tahoe Vs Synthetic Detergent oil (Mobil1) in the Vette. I am on the second engine in my car and both engines did the same thing as far as the oil color changing to black within a few minutes of running the engine.
Bill
Bill
Thread Starter
Le Mans Master
Joined: Oct 2008
Posts: 8,894
Likes: 981
From: Whitby Ont.
Are you putting Synthetic Detergent oil in the Sierra? My 03 Tahoe with 100K miles keeps the new oil color longer than my C6Z does. However, I use detergent dyno oil in the Tahoe Vs Synthetic Detergent oil (Mobil1) in the Vette. I am on the second engine in my car and both engines did the same thing as far as the oil color changing to black within a few minutes of running the engine.
Bill
Bill
Quakerstare / Sierra. Mobile 1 / corvette
will get an oil test done.
Racer
Joined: Dec 2007
Posts: 396
Likes: 5
From: Liberty Hill TX
changed the oil in my Z51 today, have changed it a few times and i thought maybe it would improve, but apparently not. i change it, comes out pretty black, put the new oil in, run it for a bit to make sure no filter leaks and etc, check it, right on the mark, but already discoloured, not very happy, is it because with the oil cooler it is not all drained out and some of the dirty oil is still in there ? can t figure it out. i changed the oil on my 2006 Sierra with 147k km, and drove it all day and still looks like it came out of the jug, and will remain like that for at least a month, but the Vette, i don t get it. any thoughts ?
Racer
Joined: Oct 2013
Posts: 252
Likes: 8
From: Charlotte NC
I'm no oil expert; but remember reading an extensive article years ago on another forum about oil. It claimed oil condition/cleanliness cannot be determined by color--that the color changes due to heat cycles/chemistry; not from contamination. Maybe someone here that knows more than I do on the subject can confirm or rebut that. Would be interesting to see how your lab results look also. Hope (and suspect) all is well!
Last edited by Wampa; Oct 6, 2014 at 10:42 AM.
Team Owner
Joined: Mar 2008
Posts: 21,502
Likes: 462
From: Southern Utah
If you are concerned, send the oil in for an inexpensive test with Blackstone...color is not a good indicator. Be sure to be honest with them as to the mileage on the engine and on the oil that you send...they factor these mileage figures into the report.
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Safety Car
Joined: Sep 2005
Posts: 4,226
Likes: 643
From: Orange County Ca
I think you're right about not getting all the old oil out. Hydrolic lifters, oil cooler, etc. Maybe you can jack up 1 side or the front/rear to get the last little bit out.
Also, I think that you are overthinking this. A LITTLE residue doesn't hurt anything.
As mentioned above, color doesn't really mean anything, unless it is REALLY black, which indicates to me a lot of short cold runs. Oil does discolor as the detergents work. If you have a little sludge build up, it may take along time to disolve it all.
Also, I think that you are overthinking this. A LITTLE residue doesn't hurt anything.
As mentioned above, color doesn't really mean anything, unless it is REALLY black, which indicates to me a lot of short cold runs. Oil does discolor as the detergents work. If you have a little sludge build up, it may take along time to disolve it all.
Thread Starter
Le Mans Master
Joined: Oct 2008
Posts: 8,894
Likes: 981
From: Whitby Ont.
I think you're right about not getting all the old oil out. Hydrolic lifters, oil cooler, etc. Maybe you can jack up 1 side or the front/rear to get the last little bit out.
Also, I think that you are overthinking this. A LITTLE residue doesn't hurt anything.
As mentioned above, color doesn't really mean anything, unless it is REALLY black, which indicates to me a lot of short cold runs. Oil does discolor as the detergents work. If you have a little sludge build up, it may take along time to disolve it all.
Also, I think that you are overthinking this. A LITTLE residue doesn't hurt anything.
As mentioned above, color doesn't really mean anything, unless it is REALLY black, which indicates to me a lot of short cold runs. Oil does discolor as the detergents work. If you have a little sludge build up, it may take along time to disolve it all.
could be over thinking, but my C5 oil looked the same after 8km as it does in the Z51 after 1000km. have an oil analysis lined up.
Team Owner
Joined: Mar 2008
Posts: 21,502
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From: Southern Utah
Safety Car
Joined: May 2011
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From: Oshawa, Ontario
lift rear
because of location of oil drain plug if rear of car is higher than front my oil will be cleaner versus not lifting rear once initially draining oil
Premium Supporting Vendor
Joined: Aug 2001
Posts: 5,364
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From: King George VA
I think that is a good call and will give you piece of mind (or not - but you'll know either way). I buy samples by the case from Blackstone and sample all my vehicles, sometimes every other oil change or so if all is well. 
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Racer
Joined: Jun 2013
Posts: 250
Likes: 12
From: Manayunk PA
One thing to think of as well is that if it comes out as clean as it went in... what cleaning did it do inside the motor? Like others said, get an analysis done and it will tell you what you need to know.
Thread Starter
Le Mans Master
Joined: Oct 2008
Posts: 8,894
Likes: 981
From: Whitby Ont.
thanks for all the input, have to put a few more miles on it, before i take some out and send it in, only got 100 since change, when i get to 500 will send it in and then when i park it for the winter, will have more on it and take another sample.
Thread Starter
Le Mans Master
Joined: Oct 2008
Posts: 8,894
Likes: 981
From: Whitby Ont.