Corvette Fluid Change Recommendations

[randomhero439]

Hello BITOG community! I recently picked up a 2008 Corvette Z06 with 47k miles on it! Reading through the owner manual, there is no recommended service intervals for the following items:

Brake fluid
Clutch fluid
Differential fluid
Transmission fluid
Power Steering fluid

I plan on driving it about 3,000-5,000 miles per year. Car will not see any extreme use such as race track conditions, but will see some trips to the drag strip and back road aggressive driving.

The fluids are almost 9 years old, should I consider changing them out?

 

[demarpaint]

Originally Posted By: randomhero439
Hello BITOG community! I recently picked up a 2008 Corvette Z06 with 47k miles on it! Reading through the owner manual, there is no recommended service intervals for the following items:

Brake fluid
Clutch fluid
Differential fluid
Transmission fluid
Power Steering fluid

I plan on driving it about 3,000-5,000 miles per year. Car will not see any extreme use such as race track conditions, but will see some trips to the drag strip and back road aggressive driving.

The fluids are almost 9 years old, should I consider changing them out?



I'd change all the fluids, especially the ATF, brake fluid, and "clutch" fluid.

 

[widman]

My first recommendation when anyone buys a used car is change all fluids. You really have no idea what is in it and how long it has been, how it was driven, etc.

 

[randomhero439]

Originally Posted By: demarpaint
Originally Posted By: randomhero439
Hello BITOG community! I recently picked up a 2008 Corvette Z06 with 47k miles on it! Reading through the owner manual, there is no recommended service intervals for the following items:

Brake fluid
Clutch fluid
Differential fluid
Transmission fluid
Power Steering fluid

I plan on driving it about 3,000-5,000 miles per year. Car will not see any extreme use such as race track conditions, but will see some trips to the drag strip and back road aggressive driving.

The fluids are almost 9 years old, should I consider changing them out?



I'd change all the fluids, especially the ATF, brake fluid, and "clutch" fluid.


How often would you recommend changing them? I plan to keep the car for many years.

 

[slacktide_bitog]

Some strips/tracks/events require annual brake fluid changes. Otherwise, I like to change the brake fluid whenever the pads and rotors are replaced. Any DOT 3 or DOT 4 will work fine. But Castrol brake fluid, if you can find it, is supposed to absorb moisture more slowly.

The clutch shares the same fluid with the brakes, and thus calls for the same fluid DOT 3 or 4.

Is your car a manual or automatic transmission? Most cars never have the transmission fluid changed, and arrive at the junkyard with their factory fill. For the automatic, Maxlife is good stuff and very popular on here. I don't5 know what the manual transmission calls for.

Power steering fluid doesn't need to be changed. But if you do it, you can use Maxlife ATF in that as well.

What does the diff call for?

 

[Cujet]

As a performance oriented motorist, I tend to be just a little hard on my equipment. Brake fluid absorbs moisture rapidly, and frequent brake fluid changes are a good idea. As for frequency, at the very least every 2 years. Better to do it annually.

Transmission fluid is another area where issues can arise due to infrequent changes. I change about every 20K miles and by that time, the fluid is in need of change. I recently lost the "light duty" transmission on my S2000 turbo, at just over 60,000 miles, input bearing failure. I'm 100% sure the 407 RWHP turbo did not help matters, but the bearing is a known issue. Had the original owner changed the trans fluid a few times, it would not have been a problem.

Same goes for the differential. 20K is a great fluid change interval for a performance car. Sure, I know you can probably go 100,000 miles between changes. That makes no sense to me, as particulates accumulate rapidly in highly loaded gearsets.

 

[oil_film_movies]

Amsoil is quality. See their recommendations at http://www.amsoil.com/lookup/auto-and-li...-e-7/us-volume/
Click on "differential" on that page for the 3 choices there. Severe Gear is great.
Fram Ultra oil filter is better than Amsoil's filters though.

 

[Mr Nice]

Some Hondas are known for the ISB going bad.


Change all fluids in your Z06.
Do you know if the valves were replaced yet before you bought it ?

 

[oil_film_movies]

Actually, here is another Amsoil "Build List" for all fluids on one page:
http://www.amsoil.com/mygarage/vehiclelookup.aspx?url2=2008+CHEVROLET+CORVETTE+7

 

[69GTX]

Change them all. For more detailed info I'd check in at the Corvette Forum for more specifics. Lots of info there. You have factory fills in your trans, differential, etc. Not a bad idea to get the leftover metal shavings out of there, especially on the manual transmission.

Brake fluid - while many recommend every 2 yrs, I don't see any issue going 5 yrs.
Clutch fluid - flush it any time the fluid starts to darken. Figure at least annually via the "Ranger Protocol." Takes about an hour and $5.
Differential fluid - 20K-30K miles is reasonable for cars not frequently raced.
Power Steering - I "Ranger" flush mine every year just to keep it fresh. Costs about $7 using GM/AC Delco fluid. This can get pretty hot on track days if your PS Cooler is weak. If the temp routinely runs above 200 deg. I'd do it annually.

Transmission fluid - Your car probably came with GM's Manual Trans and Xfer case lube in it (basically an upgraded ATF Dex3). This stuff shears fairly quickly. Figure your 7.5 cSt fluid will be down to 5.5 by around 10K miles. In your car with nearly 50K miles it must be down in the 4's by now. With a base level Dex 3 ATF-like fluid change it every 5K miles imo. If you want less trouble go with an Amsoil ATD/ATF, Mobil 1 ATF, Redline D4 ATF, or some similar synthetic. Those should get you 10K-20K miles without the problem of viscosity dropping under around 6.4 cSt. You'll get lots of inputs on this topic over at the Corvette forum. Some might be using the GM/Pennzoil Synchromesh, Royal Purple Synchromax, etc. But the T56's are typically recommended to stay with the ATF's....with the best add pack you can find. From what I've read, the Vette guys seem to favor the Amsoil ATD and/or Redline D4. Notchiness in your shifts when cold will vary quite a bit with fluid choices.

Don't forget the coolant either. Try to stay with whatever was in there originally just to ensure you don't get a bad result from mixing incompatible coolants. I'm guessing it came with orange DexCool (OAT). That doesn't mix well at all with regular green stuff. You'll have problems without a real good flush before switching. A long life DexCool Coolant should probably go 3-5 years. I do mine every 4 years. Drain and fills (rather than a full flush) are ok when done periodically.

 

[Cujet]

Originally Posted By: 69GTX


Brake fluid - while many recommend every 2 yrs, I don't see any issue going 5 yrs.


I disagree. The car in question is a Z06 Corvette, a near 200MPH car that can severely heat it's brakes during spirited driving. While I suspect the OP is going to drive it at exactly the speed limit on every occasion, and the brakes will perform properly with that old fluid. The moment the OP decides to do a track day, or other event that taxes the brakes, the 5 year old fluid will contain much moisture and will boil at a far lower temperature.

Change the fluid regularly for best results.

 

[mightymousetech]

Originally Posted By: Cujet
Originally Posted By: 69GTX


Brake fluid - while many recommend every 2 yrs, I don't see any issue going 5 yrs.


I disagree. The car in question is a Z06 Corvette, a near 200MPH car that can severely heat it's brakes during spirited driving. While I suspect the OP is going to drive it at exactly the speed limit on every occasion, and the brakes will perform properly with that old fluid. The moment the OP decides to do a track day, or other event that taxes the brakes, the 5 year old fluid will contain much moisture and will boil at a far lower temperature.

Change the fluid regularly for best results.


Agreed. My cars never have brake fluid more than 6 months old, as they often see track use.

OP's 9 year old brake fluid is probably highly water contaminated, and the brake system is probably full of algae.

 

[69GTX]

The OP can worry about how much tracking they will do with the car once they start doing it. I already recommended changing the brake fluid plus everything else. 100% fresh fluids to start.

In 6 months to 2 years from now they can worry about the brake fluid, especially since by then they will know a ton more about the car, it's use on the track, and maintenance quirks. They won't need any help from us....they'll know what to do.

 

[randomhero439]

Thanks for all the responses! I am convinced to change all the fluids. Since the car will not see many miles, I'll probably just shoot for a 5 year interval. At this time I have no plans to track it, so perhaps I will use Amsoil.

Engine oil once per year
Transmission oil every 5 years
Diff oil every 5 years
Coolant every 5 years
Brake fluid once per year
Clutch fluid once per year (I have a speed bleeder installed)

I am thinking of using Amsoil for all the fluids. Thoughts? I dont see the value in using Motul or Redline since it will not be used for racing. Or should I use OEM fluids?

What about spark plugs and air filters? Think those would be good to change every 5 years as well?

To the comment on the heads, No they have not been changed. I plan to do that next month with some AHP heads.

 

[The_Nuke]

Originally Posted By: randomhero439
Thanks for all the responses! I am convinced to change all the fluids. Since the car will not see many miles, I'll probably just shoot for a 5 year interval. At this time I have no plans to track it, so perhaps I will use Amsoil.

Engine oil once per year
Transmission oil every 5 years
Diff oil every 5 years
Coolant every 5 years
Brake fluid once per year
Clutch fluid once per year (I have a speed bleeder installed)

I am thinking of using Amsoil for all the fluids. Thoughts? I dont see the value in using Motul or Redline since it will not be used for racing. Or should I use OEM fluids?

What about spark plugs and air filters? Think those would be good to change every 5 years as well?

To the comment on the heads, No they have not been changed. I plan to do that next month with some AHP heads.




I would caution against leaving the power steering fluid off your list of service maintenances. It's no different than other fluids in that it gets dirty and worn out, resulting in it doing its job less and less effectively over time.

At the very least, I would do several drain and fills on it now so that the majority of the fluid is fresh. Then if you truly want to skip it in future maintenance intervals, you're at least giving the rack and pump a chance of surviving another 8-9 years. Leave factory fill in there and there's no way they will make it that long.

 

[oil_film_movies]

Originally Posted By: randomhero439
Thanks for all the responses! I am convinced to change all the fluids. Since the car will not see many miles, I'll probably just shoot for a 5 year interval. At this time I have no plans to track it, so perhaps I will use Amsoil.

Engine oil once per year
Transmission oil every 5 years
Diff oil every 5 years
Coolant every 5 years
Brake fluid once per year
Clutch fluid once per year (I have a speed bleeder installed)

I am thinking of using Amsoil for all the fluids. Thoughts? I dont see the value in using Motul or Redline since it will not be used for racing. Or should I use OEM fluids?

What about spark plugs and air filters? Think those would be good to change every 5 years as well?


Plugs can go ten years on a low-miles car. (Your engine computer's OBDII will tell you if you get a misfire to back you up just in case.)

Air filters easily go 30k miles (not based on time), if you're not in the desert or on dirt roads a lot.

As for fluids, you can't go wrong with Amsoil SS 5w30. However, I'd use Walmart's cheap prices on 5-quart jugs of Mobil1 Extended Protection or Annual Protection 5w30 and go 1 year on that. Or Castrol Edge Ext Perf gold jug. All dexos1 oils. Fram Ultra oil filter for sure.

Amsoil diff oil is well regarded. ... All other fluids just OEM stuff is hard to beat.

 

[69GTX]

No reason to go Amsoil on anything but the transmission fluid and/or differential, especially if it's much more costly. There are fine Mobil 1, Pennzoil Plat, Castrol Edge motor oils for that car. Same for the differential. In the end use what you like, gives good value, and peace of mind. I'd also consider changing out the fuel filter (depending on accessibility) as it may be original too.

 

[andyd]

It is called base lining. It establishes a new reference point upon which to start your maintenance records. I would start with the brake fluid first. Every fluid should at least be evaluated.