Oil Life
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Joined: Aug 2013
Posts: 71
Likes: 0
From: Middletown OH
picked up end of November, sat around in the garage most of the winter, a lot of around town driving, and one 500 mile trip.
Changed oil at 2200 miles and indicator was at 19%, vin around 7400
Z51 Vert
Dealer has a Vette only Mechanic and he did not say anything about it.
Only thing he asked is if I wanted to pay for mobile 1, or put the GM blend back in it (I forgot what it is called?) I asked his opinion, and he said take the four free ones, then switch it to full synthetic.
Did not apply, but I did ask about the 20% BS, and they said change it anytime you want up to four times.
Changed oil at 2200 miles and indicator was at 19%, vin around 7400
Z51 Vert
Dealer has a Vette only Mechanic and he did not say anything about it.
Only thing he asked is if I wanted to pay for mobile 1, or put the GM blend back in it (I forgot what it is called?) I asked his opinion, and he said take the four free ones, then switch it to full synthetic.
Did not apply, but I did ask about the 20% BS, and they said change it anytime you want up to four times.
Race Director
Joined: Jul 2010
Posts: 10,548
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From: Upstate NY
E-Ray, 3LZ, ZER, LIFT
Joined: Sep 2007
Posts: 35,045
Likes: 12,410
From: NE South Carolina
It depends on when your C7 was manufactured as elapsed time between oil changes is also concidered. My C7 born 10/13/2013, VIN 496X, was at 24% about a month and a half ago. My dealer wanted it to be under 20% to do the oil change so I continued to drive it for about 200 miles over the next month and it was now at 18%, 2200 miles total. Called dealer to schedule an oil change for the next week. Did not drive the C7 during that week until the morning to visit the dealer. Upon starting my C7 that morning 9/15 it was now at 12%, less than a month from being 1 year old. Also the owners manual says the oil should be changed annually. I suspect this is so garage queen C7s don't end up with no oil changes over multiple years due to low mileages 
Last edited by JerryU; Sep 19, 2014 at 01:14 PM.
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E-Ray, 3LZ, ZER, LIFT
Joined: Sep 2007
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From: NE South Carolina
For what it's worth, there are no sensors, strictly a computer chip checking on many variables. You have ~5500 miles in a year and probable have the oil hot much of the time you start the car. If he had the car the same length of time and only put on 1200 miles, he was starting and stopping the car frequently when the oil did not get to say 175 F. Lots of water passing the piston rings on a cold engine that did not get evaporated. That is far worse than traveling on the highway for thousands of miles. Just my thought.
Burning Brakes
Joined: Feb 2013
Posts: 861
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From: Desoto Texas
For what it's worth, there are no sensors, strictly a computer chip checking on many variables. You have ~5500 miles in a year and probable have the oil hot much of the time you start the car. If he had the car the same length of time and only put on 1200 miles, he was starting and stopping the car frequently when the oil did not get to say 175 F. Lots of water passing the piston rings on a cold engine that did not get evaporated. That is far worse than traveling on the highway for thousands of miles. Just my thought.
RThanks for info on chip no sensor for oil.R
Safety Car
Joined: Jul 2001
Posts: 4,661
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From: Ocean Springs MS
The engineer who helped develop the algorithm for the C5 OLMS used to be a member here ( may still be, but he stopped posting because too many self-styled experts were telling him he was FOS and didn't know what he was talking about.) He stated that engine, oil and ambient temperature, as well as rpm were all factored into oil life. Light use with long highway trips and you might get 8-10000 miles before a change. Take it to the track for a HPDE on a regular basis, and you might need a change after a couple weeks.
E-Ray, 3LZ, ZER, LIFT
Joined: Sep 2007
Posts: 35,045
Likes: 12,410
From: NE South Carolina
Perhaps of interest my street rod with a 502 cubic inch big block has forged aluminum pistons. When I start it sounds like a rattle! It warms up pretty quick and is fine. Aluminum has almost twice the expansion/contraction rate as steel. So the piston clearance between the block and pistons is much larger (all in thousands but larger) when cold than than when it warms up. The LT1 pistons are cast aluminum and the cylinder liners are steel so not quite as bad but until the engine warms up there is more blow-by past the rings. The products of combustion include a lot of water. So that means water is mixing with the oil when the engine is cold. It evaporates when the oil warms up but if it is not run long enough it doesn’t. GM says they monitor outside temperature, oil temperature and other parameters and set the oil life that they believe is with a conservative algorithm (ie before it is really needed.)
It’s particularly an issue with a dry sump as it holds more oil and takes longer to get hot. My wife had a dry sump in her Cayenne and although we live 15 miles from town, she is often driving to her various activities around where we live. Never could convince her that driving a ½ mile wasn’t good for the car!
Team Owner
Joined: Sep 2010
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I believe that's it. Mercedes-Benz has used the same parametric for over a decade and one half.
Last edited by Skid Row Joe; Sep 21, 2014 at 04:24 PM.
Burning Brakes
Joined: Jul 2013
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From: Cherry Hill PRNJ
Of course, to test that we would need to have 3 guys who got their cars delivered at the same time, one puts it in the garage and does not drive it for a year, one drives it 10,000 miles for a year without changing the oil and one drives it somewhere in between and see what the oil life indicator says....somehow, I don't think that experiment will ever get done.
Safety Car
Joined: Aug 2012
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It sounds like time since last change are now factored in which is good. There was always a warning in manuals before to change after X number of months regardless of what the OLM calculated percentage indicated.
Here is a link to a brief note in GM Techlink about the OLM and there was a more extensive description earlier but I couldn't find an archive that had the older issues.
Short description/note: http://www.archivedsites.com/techlin...fe-system.html
Here is a link to a brief note in GM Techlink about the OLM and there was a more extensive description earlier but I couldn't find an archive that had the older issues.
Short description/note: http://www.archivedsites.com/techlin...fe-system.html
E-Ray, 3LZ, ZER, LIFT
Joined: Sep 2007
Posts: 35,045
Likes: 12,410
From: NE South Carolina
It sounds like time since last change are now factored in which is good. There was always a warning in manuals before to change after X number of months regardless of what the OLM calculated percentage indicated.
Here is a link to a brief note in GM Techlink about the OLM and there was a more extensive description earlier but I couldn't find an archive that had the older issues.
Short description/note: http://www.archivedsites.com/techlin...fe-system.html
Here is a link to a brief note in GM Techlink about the OLM and there was a more extensive description earlier but I couldn't find an archive that had the older issues.
Short description/note: http://www.archivedsites.com/techlin...fe-system.html
How many miles can I expect to go between oil changes when using this system?
The beauty of the GM Oil Life Monitor System is that it will automatically adjust the oil change interval based engine characteristics, driving habits and the climate in which the vehicle is operated. For instance, mild highway driving in a warm climate will maximize the interval between oil changes. Depending on the vehicle, this could be in excess of 7000 miles and as high as 12,000 miles. On the other hand, short trip driving in cold a climate may limit the oil change to 3000 miles or less. In general, most people that drive a combination of city and highway schedules find that the GM Oil Life Monitor System will indicate an oil change every 7500 to 8500 miles.
Race Director
Joined: Jun 2005
Posts: 10,909
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From: Phila Suburbs 2023 C8 & 2013 650ix
I've never heard a solid argument for why oil has to be changed at least once a year independent of all other factors that affect oil life. And we're talking synthetic oil which doesn't break down like non-synthetic. I think it's based on selling oil.
If I don't drive my car for 6 months. Has my oil deteriorated 50%? I don't think so.
By way of comparison, in my 05 I drove that car 14,000 miles (50% highway) before the monitor went to 5% oil life left.
If I don't drive my car for 6 months. Has my oil deteriorated 50%? I don't think so.
By way of comparison, in my 05 I drove that car 14,000 miles (50% highway) before the monitor went to 5% oil life left.
