: More on Royal Purple....

05-03-06, 03:30 PM
Quick Q: Which weight oil...I was thinking 85W140, but all the other stuff I see is 80W90 or some similar. I dont track the car, just a daily driver, but I need to try and quiet this fooking rear. Also I can get a case cheap, so if ya want some, maybe we can work a deal....


05-03-06, 03:50 PM
Well factory calls for 75/90 I think....Id be carefull going to heavy.

05-03-06, 08:42 PM
As I mentioned earlier this week in a similar thread I run RP Max Gear 80W140 in my '05 GTO. I ran it this past winter in the GTO and maybe took a few hundred feet on the coldest day to get the LSD to work. Other than that, Dave, I think you like the decrease in noise. Probably go with something lighter next winter. Maybe it might solve the chatter.


05-03-06, 09:39 PM
Many of the Vette guys go heavier diff lube to quiet the diffs. With the track-record of our diffs, even the '06 units, going to a heavier fluid may be a proper alternative.

It won't hurt the unit, but as Norm said it thickens quite a bit in colder weather. If I was keeping my screaming-diff'd V, I'd go heavier.
Good luck,

05-03-06, 11:13 PM
As long as we're on the topic of gear oil... RP has a 75w 90, but my 03 CTS calls for 80w 90. Anybody think that using the 75 would be bad? I got some feedback on the non-V forum saying it should be fine, but would reccomend going with what the manual calls for. Any other suggestions to something besides royal purple? It's all pretty expensive, so I'm not looking for bargain basement especially if it will hurt my car. You V guys are a pretty knowlegeable bunch of gear heads, so I thought I would toss this over here as well. Thanks!