[dmau9600]

I've seen people mention changing the rear differential fluid in a few threads. Is this required after break-in, or just a good practice?

[MatthewAMEL]

It's in the HP Supplement.

Change at 1,500, after 1st track day and then after each 24 hours of track time.

[camaromike77]

Originally Posted by dmau9600

I've seen people mention changing the rear differential fluid in a few threads. Is this required after break-in, or just a good practice?

I'll be having mine done at 1500 miles...... Just "piece of mind"..... I do this with all my new vehicles..... Just my "practice" I guess........

[IrishCoffee]

Originally Posted by MatthewAMEL

It's in the HP Supplement.

Change at 1,500, after 1st track day and then after each 24 hours of track time.

I've gone over my HP Supplement several times looking for this info. Where are you finding this? Not sure if I'm blind or just have a different manual.

[Alpha1BC]

Originally Posted by IrishCoffee

I've gone over my HP Supplement several times looking for this info. Where are you finding this? Not sure if I'm blind or just have a different manual.

I saw it in the regular owner's manual, not the supplement. There's a section in the owner's manual about the break-in period, should be in there.

[G2K]

BET THIs has been asked plenty times of times.... but which sould be used... i will be tracking soon, also what tools recommended for Diy

[TrackClub]

All fluid details are in the manual...

[Alpha1BC]

Originally Posted by G2K

BET THIs has been asked plenty times of times.... but which sould be used... i will be tracking soon, also what tools recommended for Diy

I stick with OEM since it makes it easier if any warranty claims come up. AC Delco Dexron 75w90 gear fluid w/limited slip additive, GM PN 88862624. Will need 2 quarts of fluid. I think there's a list somewhere out there of approved fluids by GM, but I can't say exactly where.

Tools needed:

• New diff fluid
• jack and jack stands or ramps
• ratchet driver and extensions (no sockets, just a 3/8 square drive to remove drain and fill plugs)
• torque wrench. Can always torque stuff by hand in a pinch if needed, but I suggest making sure things are torqued properly before doing any track driving.
• rags
• oil drain pan
• pump for new fluid. I have this one, only takes a few pumps to transfer a whole quart and is pretty cheap

Steps:

1. Drive around a bit to warm the diff fluid up
2. raise vehicle so it is level
3. Remove top fill plug first, located on the driver's side of the diff. Be careful around the exhaust since it might be hot if you started the change right after driving.
4. Place catch can under drain plug and remove drain plug from the bottom rear of the diff.
5. Wipe off the shavings that have collected on the drain plug
6. Re-install drain plug to 24 ft-lbs
7. Using the pump, fill the diff with new fluid. Diff is full once the fluid reaches the fill hole (this is why you want the car to be level). Will be close to using 2 quarts since some of the fluid will still be in the pump.
8. Re-install fill plug to 24 ft-lbs
9. Wipe all the the diff fluid off everything (especially the exhaust) then you're good to go!

Also, you'll want to change your engine oil and filter before going to the track. Filter is AC Delco PF64, GM PN 12640445. And, per the high performance supplement, you'll want to change engine oil to a Dexos 2 approved 0W-40 or 5W-40. Manual specifically says you can use Valvoline SYNPOWER MST 5W-40 or M1 15W-50, but if you use 15W-50 you're supposed to change oil again after the track event. Here's a list of approved Dexos 2 oils, so you can pick the one you want with the correct weight.

[TrackClub]

Excellent advice!

Also note that the Valvoline mentioned above is now Dexos2 approved albeit not all packaging may reflect it. Also Mobil 1 ESP Formula M 5W40 is also approved according to the manual.
NB This service costs about $60 at a dealer.

EDIT: get lift points from zl1addons.com to protect the rockers when jacking the car. I have permanent ones and they work well.