Z51VetteDriver

Hello all...

I have always wondered about this. (Also on my other cars)
Concerning the oil life indicator showing the percentage of your oil life left on my C7 Vette. I have always ignored this and went by the actual mileage between oil changes. Is this the right thing to do, or should I go by the oil life percentage?

What are your thoughts on this?

Thank you very much for any valuable input...

Cheers!!!

vdavenp802

The oil life % is based on actual driving conditions, weather conditions, amount of time at speed vs stop and go. Its a complex algorithm. Probably not published anywhere, and probably differs between mfgs.
I like to look at it on a periodic basis to see how it changes over time, and if I get at or near 10% I schedule a change regardless of miles/dates. Your method is not bad it just may be you change sooner than needed or perhaps you wait too long. In my Corvette I change at least once a year regardless of miles/dates/%oil life. I drive around 5,000/yr. No track time.

millpond

Change at least once a year to keep your warranty in effect.

JerryU

This is a much shortened explanation of the monitor function from someone who understands the development-it's fine to use and a waste to change based on the "old 3000 miles etc! It uses a very complex algorithm, developed over years of work. Note, although the C6 and prior Vette Owner's Manuals always said change after a year if the indicator did not say to change sooner, the C7 integrates time into the equation. The following was heavily condensed from a post about the GM Oil Life Monitoring System by BobIsTheOilGuy. Quoting:

"...the GM oil life monitor operation and most API (American Petroleum Institute) literature uses ZDP (zinc dialkyldithiophosphate) depletion is the basis for oil deterioration. ZDP is dispersed in the oil so as to be at a potential wear site if a surface asperity happens to break thru the oil film thickness causing the dreaded metal-to-metal contact The concentration of ZDP in the oil will determine if there is ZDP present to work it's magic. ZDP is sacrificial. As ZDP is "used up" at a wear site to prevent micorwelding the concentration of ZDP decreases.... it is ONE of the basis for determining oil life remaining and is the basic premise of the GM oil life algorithm. It is only one of the things that determines oil life.
The GM engine oil life monitor counts engine revolutions and accumulates the number for the basis of the oil life calculation. It then adds deterioration factors for operating temperature, start up temperature, soak times, ambient, coolant temperature, etc. There are a LOT of factors that "adjust" or affect the slope of the deterioration but the fundamental deterioration is traced back to the ZDP depletion that is inescapable with engine revolutions.
The other things that determine oil life such as acid build up, oxidation, insuluables such as silicon from dust/dirt, carbon or soot build up from the EGR in blowby, water contamination, fuel contamination, etc.... are all modeled by the multipliers or deterioration factors that "adjust" the immediate slope of the line defined by the engine revolution counter as those items can be modeled in other ways and accounted for in the immediate slope of the ZDP depletion line.
The algorithm was developed over the course of many years by several lubrication experts at GM Fuels and Lubes, spearheaded by Doctor Shirley Schwartz who holds the patents (with GM) for the algorithm and the oil life monitor. I had the luck of working directly with Dr. Schwartz when the idea of the oil life monitor first progressed from the theoretical/lab stage to real world testing/development/validation.
There are entire SAE papers written on the GM oil life monitor and one could write a book on it so it is hard to touch on all aspects of it in a single post."


IMO many who drive their Vettes infrequently and worse drive only a short distance before the oil heats up are tougher on lubrication than those who drive longer distances. The monitor takes these factors into consideration. The C7 now uses time as well, as it should, so if storing over the winter the monitor will read less available time left after storage!

Z51VetteDriver

Thanks guys. I only drive it on nice days. I changed the oil after the first 500 miles. Now I have 1,900 miles on it and the oil life indicator is at 7%. LOL!!!
I think the mechanic most likely forgot to reset it. Which seems to happen a lot now days.
But yes, I do/will change it every year regardless of mileage or percentage.

Thanks loads for all of your input!

Cheers!!!

JerryU

Others have reported as it approaches 12 months from the last resitting it will read close to zero regardless of miles!
I change the oil in my Street Rod every year with less than 1000 miles! Now it mostly only goes to car shows and I try to always drive it ~15 miles when I start it to get the oil warm! Moisture still condenses in the crankcase with all the humidity and temperature changes we have, and there can be an acid build-up. Cheap insurance to keep the Chevy BB in good shape!

bbcb

imo the thing is a waste ......

Z51VetteDriver

I'm kinda leaning that way myself. They never had this oil life indicator on cars until the last few years. I just have always changed my oil every 3000-5000 miles. Or I'll change it if it's been a year, regardless of mileage. I also use synthetic oil in my Vette also...

JerryU

Per my post #4, I quoted about 25% of what the fellow posted presenting excellent facts since I know some folks eye's roll when tech "stuff" is mentioned!
The old days of changing with miles is just that "old days logic" (or that of Jiffy Lub etc. and some unscrupulous dealers) especially if using "full synthetic." Heck some of those oils say change at 15,000 miles, which I would NEVER do!
Even my 1988 Vette had an oil monitor, about the same time it was introduced by GM. Since you'll change oil every year minimum (which it says to do in the Owner's Manual) that is probably OK! But if you just make many short trips and oil doesn't get warm it's possible the monitor will say to change sooner! GM is not in the oil business so it's not a conspiracy to have you buy more!

PS: Could never convince the wife that is was not good to travel 1 mile to her girlfriends with the dry sump in her Porsche Cayenne, so expect there will be those who prefer not listing to facts!

Larry/car

I don 't get over excited about changing oil. I purchased a car that sat in storage for years with the dirtiest tar like oil you ever saw. No harm was done, I even dropped the oil pan . I serviced with new oil, engine performed flawlessly. I still watch mileage, calender time is secondary. I don't subscribe to the once a year rule. Oh, I change
my truck's oil at 15,000 mile intervals. It has over 140,000 miles, performs like new and I do not need to add oil between changes. Go figure?

meyerweb

Changing oil at that mileage / interval certainly won't hurt anything, other than possibly your bank balance.

Here's the full write-up about the OLI than Jerry copied some of, above. The people who developed it did a lot more testing, and are probably a lot smarter, than most of us.

https://www.corvetteforum.com/forums...post1589362444

fdxpilot

One of the engineers who helped develop the C5 OLMS used to be a member here. He stopped posting because he was tired of vette owners telling him he didn't know what he was talking about. Based on his info, the OLMS takes into account oil and engine temp, rpm, mileage, and with the advent of the C7, time, to figure oil life. It starts with a baseline mileage, and then subtracts based on these factors. The baseline mileage was initially 10000mi, but was later upped to 15k IIRC.

If used strictly for long highway trips, you might get over 10k mi before its time to change. Lots of short trips, like many vette owners do, will give you a shorter interval. A couple of weekends at the track will probably exhaust your oil life in that time, if you don't change it anyway after tha track session. And as mentioned, with C7s, at one year, your oil life should drop to 0, even if you didn't drive it a mile. Personally, I got up to 4900 mi (4400 after the 500mi first change) on my Z06 before my life got down to 11%, while my wife, who is a little more sedate, gets about 6000 mi between changes on her Stingray.

JerryU

It is a shame he felt the need to no longer post as I find the benefit of this Forum is trying to convince folks that facts, as I see them, should out way personal opinions! If you stick with it you’re often finally vindicated!
My insistence for over 2 years that my coupe hatch would not latch without a door opened is an example. For some whose C7 coupe hatch did latch using the GM handhold could not accept those of us where is would not just didn’t know how! We were accused of not being strong enough or having a weak wrist as when improperly using a semi-automatic pistol! With persistence those who posted or supported they had the issue or that their hatch frame paint cracked due to pressing to latch were justified when GM reverted back to the motorized pull-down for the 2016 model! Perhaps the new Camaro having a built in "Catch Can" of sorts will justify those of us who feel it's a worth while addition!

Have a similar feeling about the oil monitor system! If I can’t provide accurate info on why it works, I keep on trying with improved communication or finding I'm wrong! Can’t convince everyone but hopefully the dialog is useful for the silent minority who read posts but don’t actively participate! Being semi-retired I have the time and inclination to try!

I’m just an old Hot Rodder and have been for 60 years! Learn a lot by reading all the car mags for those years and now with the internet the many reports on the C7 etc. that are easy to search. I enjoy the challenge and when wrong admitting my postulate is incorrect and learning! Forums are a great source of info but need folks who will share experiences and knowledge.

Glen e

the oil minder system is great for a non-enthusiast that treats their car like an appliance. It keeps your admin asst from turning his/her oil into sludge at 20K miles.

If you a forum guy, you will come up with your own change schedule, most likely....

rcooper

Lots of good info posted here...but here is the simple answer. Chevy?GM spent lots of money designing the program that tells you when to change the oil. They base their warranty on these parameters. If it is good enough for them, it should be good enough for you.

JerryU

But quoting what meyerweb stated above: "Changing oil at that mileage / interval (~3000 miles) certainly won't hurt anything, other than possibly your bank balance."
As long as you're changing BEFORE the oil Life Monitor says to - fine! However if you use your Vette infrequently and only make short trips where the oil never gets hot, then store it for the winter, and elect not to "believe" the Life Monitor (which now also includes time) then your not changing frequently enough!

Z51VetteDriver

"Changing oil at that mileage / interval (~3000 miles) certainly won't hurt anything, other than possibly your bank balance."



If one is worried about their bank account, one shouldn't own a Vette!
LOL!!!

JerryU

Since you asked the original question, you certainly can change it if you "don't like the color" or before the Life Monitor says to based on your idea of what mileage makes you feel better, your choice!

rothchilds

Wow, pessimistic much some of us that are not administrative assistants are pretty damm busy. I follow the minder, usually end up changing around 15%, which ends up being about 8500 with my driving conditions. A lot of tech went into the monitors, I see no reason to discard it and think I am smarter then those who created it.

And besides, I forget a lot of things. Nice to know this is never one of them

meyerweb

I'm a forum guy, but don't think I'm smarter than the engineers who developed the OLM.