I bought my 2009 base Z51 Automatic three years ago. It had 89904 miles on it. I bought this car from a dealer and I was unable to confirm past owner or maintenance for the car. I decided to start with a know good value on the fluids in the car. I had ALL fluids changed at that time. I have changed nothing since. The car now has 92,098 miles on it, or about 2k per year.

I am now starting to wonder about the DIC's display of 59% oil values left. The purpose of this note to to see what others are doing as to changing fluids, especially oil. Does anyone use or trust the DIC numbers or do you change fluids on a different schedule?

Given its 98 deg outside its hard to imagine 3 year old oil being good for the car.

Thanks, Jim

 

Change the motor oil yearly, or every 12K miles, which every comes first.

As for DIC oil percentage (used both mileage and how hard the motor is pushed in that time to come up with values), guess if you are driving the car for 12K in a year, would trust it slightly, but would still pull the dipstick once in a while to check oil level, and keep an eye on the how dirty the oil is, since may need to be changed more often then every 12K.

 

Since you bought the car used and don't know the history, here's what I'd do.
Look at the oil. IF it's very dark, I'd definitely change it. IF it's relitively clean, I'd let it go.
On my '69, that I don't drive a lot, I regularly go 2-3 yrs between changes.
5k miles OR, as needed. Engine internals are very clean, no sludge.
I always try to get a car up to full temperature whenever driving. Short, cold, drives are not good. Got to get the temp up to evaporate any moisture, etc..
I sometime change at less than 5k, IF the oil looks especially dirty.
Another thought. If your engine wasn't maintained regularly, it may be a little dirty inside, and a short routine change may help clean it up.
Then again, changing early doesn't hurt anything--may not necessially help, but won't hurt.
I do my own changes which are cheap for about $40 for high quality oil and filter. Price may be a factor if you're paying $150+- at a dealer.
Oil related engine problems are fairly rare, even with some members here going 10k miles between changes. Newer engines with direct injection are a different story.

 

I look at oil as a very minor cost compared to the worry and potential issues.Less than $50 a year is cheap piece of mind for me.My mileage is always less than 4 or 5k a year on any of my vettes.

 

Do what makes you feel good abut it. I do about 7k miles yearly. Change oil at 5k and thats also 50% life on the dash. Did the trans oil last year at around 90k miles and I suck out and replace the brake fluid from the reservoir every few months.

 

I've got 93k on my 08 now, and the DIC says I'm at 56% but I last changed my oil in July last year with 89k on the odometer. I plan to change the oil next month regardless of the DIC. Like jamieo said, it's cheap insurance having fresh oil and filter for warm summer drives. Since you have an automatic it won't be an issue for you but I also do the ranger method for the clutch fluid in my manual trans at the same time.