My 2008 has 12214 miles..no records of anything other than oil and filter being changed! Mileage wise probably not needed,age-wise I would think it should be done? Trans fluid,rear end fluid and yes it has very minimal chatter but it's still there! What other fluid should be done?

 

May want to post this in the proper forum if you want answers.

 

Thanks..

 

You can also request the mods to move this to C6 Tech. That way you don't have two posts on the same topic.

As for fluids. Oil is obviously most important, and it should be changed annually regardless of mileage. The OLMS on the early C6 cars doesn't take the calendar into account, so you have to remember the annual oil change yourself. If you drive it a lot, the OLMS will tell you when the oil needs to be changed. Remember to reset it at every oil change. Mobil 1 or Pennzoil Platinum full synthetic are the only oils I'd recommend for these engines.

Differential fluid should be changed early (first or second oil change), and then it lasts a very long time. There's an age component to that one as well, but it's more like 5 to 10 years for that fluid. I've never seen a differential/final drive unit damaged from neglect, as long as there was no leaks, and provided the initial fluid change was done.

Coolant should be changed every 5 years. Most folks use DexCool. That's what GM puts in at the factory. It's a good coolant, but it doesn't respond well to neglect. If it's never been changed, you're way past due, and possibly into the time when old coolant causes other damage. It gets acidic with age and it will eat gaskets, heater cores, and radiators. Use a mix of fresh coolant ("concentrate") and distilled water, or buy pre-mixed coolant.

Brake fluid (and clutch fluid) should also be changed. My habit is to do that every 2 to 3 years, with one brake fluid flush at every coolant service, and one more in between each coolant service.

There's a pretty thorough maintenance schedule in the owner's manual. If you don't have the manual for yours, those are available online from GM.

 

First and foremost, Welcome to the forum and congrats on the new to you '08 Vette.

You'll find lots of information and opinions here. The hard part will be sorting out the accurate from the good intentioned opinions. Timing of maintenance is a subject full of opinions because there are no hard and fast rules that apply to every car, every driver, or every circumstance. You need to create your own opinion, based on way too many factors to list here. Keep in mind that a Vette is still just a car that each individual can and do use in the way that suits them.

One piece of information that relates directly to your question, is about differential fluid. The factory fill was changed from an individual 2-part lubricant to a pre-mixed lubricant about midway during the 2008 MY run, specifically due to chatter when/if the components were not mixed in the correct proportions. GM issued a service bulletin to dealers, advising them to change to the new fluid for customers who complained of chatter. Just because this known possibility may exist on your '08, I'd advise changing the fluid to the newer one which is AC Delco Dexron 75W-90 LS gear oil part number 88862624. The bulletin told dealers to do several figure 8's to work the fluid into the clutch plates before returning the car to the owner. However, that's not necessary, since normal driving will do the same thing, just not as quickly. If the chatter doesn't stop in the first 100 or so, left and right turns, the noise may be related to another known early mileage issue, of loose axle nuts. They need to be tightened to 140 lb ft.

As far as other maintenance is concerned, my wife has a '08 Cadillac STS, bought new, and handles her own maintenance. It's currently at 118K miles with the original factory brake fluid, trans fluid, coolant, PS fluid, axle lube, and AC. The front brake pads and wheel hubs were changed once, she's on her 2nd air filter, 3rd set of tires, the 4th battery, and only had two minor problems (EGR valve and door switch) in 12 years. She does get the engine oil and filter changed about the time the OLM is 5% or less, since she feels that's the only thing that is really necessary beyond gas.
So you can see that there are extremes and the GM intervals are just recommendations.

 

Fluids you should do:
Trans fluid
Diff Fluid
Oil and filer (if it has not been changed in over 3,000 miles)

With that said it would not hurt to also do:
Brake Fluid (use a good dot 4 fluid), Coolant drain and refill along with replacing the PS fluid

If funds are sparse or just not wanting to spend at the moment then just do the diff and trans.
The diff has a limited slip modifier in it that wears out over time and is a required additive in the fluid to keep the clutch's in the diff happy.

If your a M6 trans then do the ranger method for the clutch fluid.
Also not a bad time to do plugs and wires if they were not done in the last 60,000 miles.



https://americanheritageperformance.com/

 

I would strongly recommend doing the coolant change. I've replaced or bypassed a ton of heater cores on 10-20 year old GM vehicles with neglected coolant. The problem is present on other makes, but GM vehicles which were filled with DexCool are particularly at risk. DexCool is technically a slightly better coolant than other "extended life" coolants, but it gets acidic when it ages past it's usable service life. If neglected long enough, it will start etching (disolving) the metal of the heater core and radiator. DexCool also reacts poorly to aeration, especially when it's past it's usable service life. So when you have a leak in the system, the DexCool coolant can have various reactions that can corrode the insides of the radiator and heater core, or just clog them with a muddy, "jelled" gunk.

The labor to replace a heater core, even if you do it yourself, is horrendous. Even an "easy" job like replacing a clogged or leaking radiator isn't as easy in a Corvette of any generation as it is in most other cars and trucks.

Remember to put a new pressure cap on the thing when you do that. The springs wear out and they rarely hold the required pressure after 5 years. I've also fixed countless "mysterious coolant loss" issues with a new cap, often after those vehicles have been to other shops and taken heavy hits from the parts cannon (thermostats, water pumps, even head gaskets).

All I'll say about brake fluid is, if it's dark in color, you'll get a firmer pedal if you change it. 95% of the "improvement" people report when they install braided stainless brake flex lines in place of rubber ones is from the fresh fluid. If you leave the old brake fluid in long enough, it also gets acidic and starts to etch/eat parts.