GoatHead

I have 17' GS with 2k miles. I am going to HPDE this Friday and Sat. According to the manual, I need to replace the rear axle fluid after the first track day. However, I came across a thread about the importance to change the fluid after 500 miles.

I've already ordered the fluid, but I may not have time to replace it before the HPDE. Will the car be ok?

Thanks,

Donatella

I had my differential fluid changed after the 1,500 mile break-in required for track use...Then every 25 engine hours thereafter...The manual does say change after the first competitive driving event. You should be fine..

Bill Dearborn

Do what the manual says. Change the fluid after the first track event and then every 24 hours of track time after that. Several years ago GM didn't say to do anything special for the diff when running track events. Then in 2009 the OM suddenly said to change the oil every 24 hours of track use and then with the C7 the requirement to change after the first even was added. Think there may be a lessons learned story in there some place???

Bill

George_L

I haven't tracked my car but I changed the diff fluid this summer after 5000 miles and it was a very silver color leading me to believe that there were a lot of metalic particals in the fluid. The magnetic drain plug was much covered also. If i buy a new vette I'll change it early, sometime shortly after the break in period.

Bill Dearborn

It can't hurt but is clearly overkill since most people never change the fluid throughout the lifetime of the car and have no diff problems. Track usage brings diff temperatures to very high levels compared to non track usage and that is why GM recommends changing very often when tracking the car.

Bill

k24556

A lot of street-only drivers had a chattering of the diff due to contaminated fluid. The diff is vented, so damp air can enter, and when the fluid gets hot it will pick up moisture. Then heat it back up and you have a recipe for a tiny bit of corrosion to occur.. Most the black crud on the magnetic drain plug is magnetite, an iron oxide and corrosion product when there are low oxygen conditions. Lots of dissolved oxygen will give hematite, what most of us call red rust. Not a big deal but when you want to diff clutches to slip, they need to slip. Add ELSD, and you need pristine fluid for track duty. Run on a rainy day at the track (we missed you at VIR, BIll, last Thursday in the hurricane)..... you get the picture.