Does the percentage go down in time also or is it just while engine is running. Got my 500 mile change on time. Put 2k more on it prior to putting up for winter. Just looked today and saw that % is at 27% life. I can't believe that it went to that in less than 3k miles. Or is that possible. I did not look at percentage prior to putting it up for the winter.

 

Time and mileage.

 

The algorithms in the C7 OLM contain a component for time, whether the engine is running or not. If you changed the oil and reset the OLM to 100% and didn't drive the car for a year, the OLM would show 0%. The C6 OLM did not have the time component.

 

Thanks guys.

 

Complex algorithm. Takes into consideration after you start the engine does the oil get hot enough to evaporate the water that is a main product of combustion. On a cold start/rich mixture more gets blowby gets past the rings etc.

However like all of my 5 Vettes it tells you to change a minimum every year! But this is the first Vette that keeps track of time for you!

Checked my '93 Owner's Manual that says for normal driving change at 7000 miles or 1 year whichever occurs first.

It also says if most trips are less than 4 miles change every 3000 miles or 3 months!

 

Do I really need to change 10 quarts of 0-40 every year with inly 4,000 miles on it?

 

Only if you want GM to cover any (oil-related) engine problem under warranty.

 

Believe it. It's time calibrated too. If you think that your oil with only 2K miles usage on it is 73% gone, you're buying into the myth of changing it when it's not even close to needing to do so.

 

Oil is cheaper than a new engine.

 

When changing your own oil so you just keep a record of the change in case of a warranty issue?

 

I just got the vette out of winter hibernation yesterday and was puzzled to see the notice to change the oil with only 4600 miles since the last oil change. OnStar also sent me a notice that I was at 0% oil life. I checked my records and saw that it's been a full year since I last changed the oil.
I too was unaware that the oil has to be changed each year regardless if under the 7500 miles recommended interval.

 

Throwing the time in there allows them to sell more oil/labor for the changes as well. Great marketing on their end as the average customer would get it changed if they had only put 200 miles on it since the last change

 

I bought a new Grand Sport last September. I drove it 500 miles and had my first oil change. Since then I drove it 100 miles and put it away for the winter. I took the car out last weekend and have driven another 50 miles so the car has a total of 650 miles. I'm showing 26% oil left which is ridiculous. I understand the algorithm etc and the car gets "free" oil changes by the dealership for the first few but I was told by a mechanic to go to my DIC and simply change it back to 100% given the circumstances. I would normally change the oil at the 20-25% mark anyway so I don't think it's that big of a deal?

 

Is the mechanic going to repair the engine for free in case of a failure?

The probability of something happening is very low but the cost of a failure is very high. I make sure I have the records to back up that I have followed the GM required maintenance.

 

I drive the Vette enough each year to need to change the oil once a year.
But IMO there's some leeway when it comes to changing the oil, or not, after 12 months.
A few extra miles isn't going to hurt anything.
But it depends on how the car is driven and for how long it is driven each time the engine is started during a 12 month time.
Multiple short trips, less than 20 miles each time is bad for oil life because the oil will not get hot enough, "for long enough", to burn off water condensation etc in the engine when it's fired up.
This causes acids/contaminants etc to build up in the oil and sit there until the next engine start.
Driven that way the Oil Life Monitor % will go down faster than normal regardless of time elapsed, driven or not.
That's its purpose and how it works.

Putting the car away for winter and changing the oil without starting the engine is not a problem IMO.
Spring comes and the OLM % is down low with Clean oil is one thing.
But a car driven only short distances for short periods a few times "after" an oil change, and then put away for the winter, is something else.

I don't start my Vette unless it's going to be driven at least 40 miles or more for the day.
And pretty much use it as my DD in the Summer, but not for short errands, unless I'm going to continue driving it many more miles afterwards.

Changed the oil/filter last year 05-05-2017 right before driving from MA to FL and back, with more miles put on after returning home.
That was 85-90 % highway miles.
Changed the oil 3 months later on 08-10-2017 when the OLM % hit 25% with 4,850 miles on the oil change.

Today 04-27-2018 almost 9 months later and 2,875 miles the OLM is at 25%.
If I wait, 08-10-2018 will be 12 months since the last oil change and OLM will hit 0% on, or before then.
When I've checked oil level before each oil change, the level is still where it was when filled from the last oil change.
And the oil still looks good on the dipstick, although it looks black when it's drained

It's cheap insurance to change the oil and I get ready to change it shortly after the OLM hits 25%.
I also have to decide when to change it earlier if it's close to putting it away for winter, or near 12 months since the last oil change.

It helps in certain situations deciding when to change the oil or not, to consider how the car is driven.

 

I say drain the oil when it says and use the old oil from the C7 in another car. I have
a 2008 Uplander and rather than disposing the oil, I change the oil in the Uplander since it's out of warranty anyway and add the lightly used (1500 mile) C7 oil and go 3K on it in the Uplander. They want us to recycle, so I recycle.........I also have a 2003 Honda Accord I can use 4 quarts in when it's time.
Odd how they make all the claims and brag about the qualities of the synthetic oils yet you have to follow a procedure that was changed causing the owner to abide by the rules or suffer the Wrath of Khan.
Throw common sense out the window along with the baby and the bath water and forget trying to make any sense of this issue.

 

I used to change the oil in my C6 every two years and the oil analysis results showed the oil was still in good shape. But I wouldn't do that with a C7 under warranty by any means. And I think 1 year maximum is a safe interval since not everyone wants to do oil analysis in order to see the condition of their oil. That one year oil change is especially important with a direct injected engine due to the possibility of higher levels of fuel dilution in the oil.

 

Used oil deteriorates over time, regardless of whether the engine is running.

And you don't HAVE to change the oil when the DIC says. If you think you know better, then do your own thing, but then you have to take responsibility for the consequences.

However, if you want the factory warranty, and have the factory take responsibility for damages, then you have to abide by the rules set by the factory.

Seems so simple, and yet some people want to play by their own rules, but still have others take the responsibility.

 

New oil still in the unopened container deteriorates over time as well.

 

It's easy now! I keep the original receipts in an envelope with my Owner's Manual

I buy from Walmart, 5-30 dexos approved Mobil 1 for $25 for a 5 quart jug. I buy two for the dry sump.

I scan the receipts as that is all Mobil requires for the $12 rebate per jug (two allowed.) So I pay $2.60/quart and the whole job is done in much less time than going to the dealer!

AND I am sure:
My rocker panels are not cracked form improper lifting,
The oil isn't overfilled,
It is really Mobil 1,
The fitter is not over tighten nor are the two drain plugs.

Plus I look at the magnets on the drain plugs I installed at the 500 mile oil change!