Gearhead Jim

The OLI on the C7 counts time, in addition to the other parameters we are familiar with.

My understanding is that if you got the oil changed and the indicator set back to 0, and didn't start the car at all, after six months the OLI would show about 50% remaining and after a year it would be at 0%.

My understanding is that if you got the oil changed and the indicator set back to 0, then went off on a long/fast road trip within a week, after about 4,000 miles the OLI would be down to about 50% and after about 8,000 miles it would be down to about 0% (depending on driving conditions, of course). Even though the oil had been changed only a week ago.

How do those two things combine?
If you used up half of the oil life in a quick/fast drive, the OLI would be down to 50%. If you then parked the car for six months, would the OLI go to 0% even though you had "used" only 50% of the life and it was only six months from the last change?
Or does the system calculate the life used by driving, and the life used by time, and apply the most extreme of the two but not both at once?

owc6

It uses everything the C6 did (driving style, trip lengths, conditions........................and so on...).

The C7 has added time in addition to all the other factors (will zero out at ~ one year, regardless ). I would also bet it's added other new metrics as well (that we aren't aware of), so yes, change the oil, drive 8000 miles and it will read at zero. That's how it's worked for me

Time is not a real factor for me, but I do get just about your 7500-8000 mile estimate on my oil changes (dry sump).

If you change the oil, drive 4000 miles in a week or two and then park it, it will definitely time out at a year, probably before that (by a month or two). However, this is a situation that is highly unlikely to happen, given owners are driving or not. Most have not bought the car to do a road trip and then park. JMHO

Patman

I wish someone from GM would clarify how the C7's oil life system really works compared to previous generations, we all know about the new time factor now but Jim raises some interesting points about how the mileage and time factors can possibly clash in this system. There is also another factor that I wonder about. Do the dry sump cars allow for a longer interval? Because in reality they should, with 10 quarts vs 7 quarts, you should be able to go 30% longer on that oil, as the TBN can stay stronger for longer, and any contamination that gets into the oil is more diluted with that larger capacity.

rrsperry

Jeez still? Just change the oil every year while it's under warranty. After that, do what you want. Ignore it, reset it, change it when Blackstone analysis tells you too.. whatever.

eboggs_jkvl

The system isn't that smart. It's not testing the oil but is only calculating on parameters. When you reset it, the clock restarts and you begin anew even if the oil isn't new. The system reads through it's list of parameters and starts a new "Change the Oil" timeline. If you drive enough miles, before 12 months transpires, it calls for an oil change. If you only drive 1 mile and park it for 12 months, it'll ask for an oil change again when you start it up.

Elmer

Foosh

It's not just mileage-based. It also factors in the number of starts, idle time, and RPM. A lot of starts and shutdowns indicates short trips, which will shorten the interval. High RPM and extensive idling will do the same. You can drive 1000 miles at relatively low RPM, vs. 1000 miles at relatively high RPM, and the latter will show less oil life left. Similarly, 100 engine starts in 1000 miles, will shorten the oil life more than 10 engine starts in 1000 miles.

Gearhead Jim

My question remains.

Does the C7 OLI take the time "penalty" and the miles/temperature/etc "penalty" and add them together, or does it just take the worst of the two and ignore the other?

If it adds them together, then 6 months with a 4,000 mile highway trip would put you down to about 0%.
If it takes the worst one and ignores the other, then that 6 months + 4,000 highway miles would put you at about 50%.
Big difference.
Or there may be some blending of the data.

Due to high miles driven, I do about 2 oil changes per year anyway but would like to know how the system calculates.

MMD

owc6

I do believe I answered this as closely as anyone can.

mschuyler

Nobody knows the exact answer. We've done as well as we can on this forum. We've just had an EXTENSIVE discussion of the OLM here. If you find out the exact formula, be sure and let us know.

No, it doesn't mean that and no, the question makes no sense.

Avanti

Since it is owner re-settable, you can do with it as you wish. The only issue then might be potential warranty questions if one had a motor/lubricant related problem...

Gearhead Jim

Thanks for your posts, but I'm having trouble understanding your reply.
In post #7, I listed two possible ways the OLI can handle the time vs miles issue, can you tell me which one you think it uses? Or some third combination?

owc6

As I said in post #2, paragraph two, sentence one: Time is now in addition to all the other parameters. It's not an either-or-situation.

It uses all the metrics to determine when the oil should be changed. Hopefully this clears up your confusion.

Patman

No, because oil in a sealed bottle does not degrade. But if you pour that oil into your engine and then start running it, it gets contamination in it, which will cause it to start to degrade.

JFJr

Over time the by-products of combustion get into your oil, synthetic or petroleum, doesn't matter. That causes the additives to lose their effectiveness, so periodic oil changes are needed.

jimmbbo

Every car I have owned since 2003 had both time and calendar limits, likely decided by the assumption that the car will be driven varying distances by various owners during the time interval, exposing the oil to varying amounts of water, combustion byproducts and other contaminants that adversely affect oil life, and on average, a time was chosen to ensure the oil wouldn't deteriorate. Absent individual driver data to the contrary, an arbitrary time limit makes sense.
Oil in a sealed container is not subjected to such environmental conditions.

MMD

Gearhead Jim

If you are under warranty or extended warranty, you need to play by GM rules if you want to keep the coverage.
If you are out of warranty or don't care, do whatever you think is appropriate.

Your car, your money, your choice.

Vetteman Jack

If it has not already been done, perhaps this would be a good Ask Tadge question. It would be interesting to know more about the newer OLM system.

Gearhead Jim

Pat-
Go for it. I'll vote for you being question of the month.