Has anyone on the form ever questions the accuracy of the Oil Life % and Oil Low indicator?
Take into account, the actual oil level indicator on the dip stick is within tolerance.
I just don't understand the algorithm used to calculate Oil Life.
I really don't drive my vette that hard.
The Oil level stays consistent between changes.
Doesn’t the type of oil, Synthetic, require less trips to get changed and increases mileage between changes?

Naturally, this is all based on your driving habits. But I would expect to get more oil mileage on my weekend mostly, short trips and rarely punched Corvette.

I could be just over reacting, but I just wanted other vette owners point of view.

Thanks

 

Do you have a problem with the amount of time the oil indicator is giving you? Do you think it is too short? Do a search on oil and you will see many opinions. Before Mobil 1 recommended to go by your owners manuel, they stated 12000 miles or 12 months. If you have the stock air filter on, and no power adders I would not worry about and just go by the indicator. People like me with a high flow filter know we need to change a little sooner than the indicator, it does not know I have changed the air filter.

 

Your oil life is primarily based on engine revolutions and engine temperature, and not based on engine mileage. During the winter months, due to low engine temperature startups, you should not obtain the same mileage between oil changes as during the spring/summer months when the engine is started in warmer weather. Cold weather is hard on oil life.
The algorithms used are written for the stock engine setup, so some mods will affect when your oil requires changing, but cannot affect the actual algorithm. A different air filter should not affect the changes, as long as it filters out as much or a greater amount of dirt particles. More air entering the engine should not affect the oil life monitoring system calculations, unless it is allowing a greater amount of dirt to enter. Most high-flow air filters (not all) filter a lot better than the stock paper element; or so they say.
The algorithms are also written for synthetic oil that meets or exceeds GM spec requirements. Using oil that does not meet these specs means the calculation for when your oil change is required will not be accurate.
The computer cannot determine the type of oil used or amount of dirt that is entering the engine, so if you live in a dusty area, you should change your oil more often.
For your own well-being, you can always have an oil sample checked to see how it held up over the miles. There are some companies that will do this for about $20.00 per sample.

 

Thanks for the reply. I really don't have a problem, I just don't know what to expect and wanted to get others point of view. I change the Oil twice a year on the vette because that's what it indicates. I dirive it from late March to early November. But I do the same with my other cars that I drive less than 10K a year and they don't use Mobile One. I'm just not sure if I'm changing the oil because it really needs it, or I'm chanking the oil because of an indicator.

Thanks for the help

 

That is all great info....anyone know the answer to the "oil low indicator" though and how it works?

 

My C5's typical duty cycle is start-up and 5 miles, 4 times a day. My DIC typically shows zero oil life after 3500 miles, which is about 6 months. The conventional wisdom on this driving style is that condensation in the oil does not get evaporated out due to high oil temperatures, so I change my Mobil 1 per the DIC. When I had a C4, the duty cycle was the same, but I changed the Mobil 1 every year, about 7k miles. That car has about 140k on it now, so it appears I didn't do anything wrong with it. With the $$ invested the C5, it's probably a little extra insurance, $ 35 for a DIY oil change. Like you, I'd like to know what goes into the "Oil Life" algorythem. I suspect a start-up 5 mile trip uses as much oil life as a 100 mile trip. Go longer and it probably costs more life. I'd like to believe the algorythem is more complicated than simply counting starts. :cheers:

 

I recently changed my oil at 49% and then sent the oil out for analysis. The report came back with a TBN of 10, which shows there was quite a bit of life left in the oil. I am using Amsoil 5W-30 (ASL). If you are really concerned, monitor the oil life and do some oil analysis. It is the only way to tell for sure. However, since GM is basing their oil changes and in effect their warranty on this monitor, I think it is a safe bet that it is somewhat conservative.

 

Since the algorithm is based upon engine temperature and rpm, the computer does take into account how long the engine has been running.
For example, if you start the engine at 20 degrees, run it for x-rpms until the oil gets to 120 degrees, then shut off the engine. The computer algorithm knows the engine oil did not get up to operating temperature. Now, if you start the engine at 20 degrees, run it at all rpm ranges, and the oil temp reaches 190 degrees and stays there for a while, the computer knows that water vapor should have been burned out of the oil supply.
I have changed my oil in late Nov. did my typical two mile drive to work, two mile drive home, and watched the oil life monitor drop to 80 percent very quickly. Then come end of December, and I go on a 650 mile trip, I see the oil life monitor only drop about 5 percent. So, the algorithm does take into account how long the engine is run and at what the oil temp is at engine startup and turn off, as well as the rpms the engine was run at during operation.
Synthetic oil does not break down like conventional petroleum based oils, and even conventional (non-synthetic) have improved considerably in the last five-to-six years.
Basically, the three thousand mile oil change is pushed by those companies who make money on people changing their oil...oil companies, garages, even dealers. Just remember, the oil life monitoring system cannot take into account dirt entering the engine. This is where the cost of a good filter pays for itself. And I have to stress it again, the algorithm is based upon the usage of a synthetic oil that meets certain specifications set by GM, and this can be any synthetic oil, not just Mobil 1.

 

Good info, White, RPM do make a difference on the oil life indicator. When I "race" her the oil like drops fast, BUT it can not take into account how much fresh oil I have to add due to consumption. So when the indicator gets below 20% during the summer when I was running hard I'm not to worried becuase I have added 4 to 5 quarts during the last 80% of oil life. Just know your car, your environment, your airfilter, and the indicator.

 

Great information guys, thanks for your input. :thumbs: