Royal purple in DIFF?

[happycamper]

I used Mobil1 75W-90 LS Synth, and now have grinding noise when making turns. So, I bought the GM friction modifier and will be trying that.

I suggest buying the RP Max gear, which already has the modifier. It costs less that Mobil1 + modifier.

[Coyotekiller]

Originally Posted by happycamper

I used Mobil1 75W-90 LS Synth, and now have grinding noise when making turns. So, I bought the GM friction modifier and will be trying that.

I suggest buying the RP Max gear, which already has the modifier. It costs less that Mobil1 + modifier.

You should have added the modifier with your new gear oil. My dealer made sure I had it when I changed mine to the Royal Purple Max Gear. I assured them it was already mixed in.

[Synner]

Originally Posted by happycamper

I used Mobil1 75W-90 LS Synth, and now have grinding noise when making turns. So, I bought the GM friction modifier and will be trying that.

I suggest buying the RP Max gear, which already has the modifier. It costs less that Mobil1 + modifier.

The LS in Mobil 1 stands for limited slip. Both it and RP already have the additive, some diffs just seem to like some extra. I bought the additive to mix in with the RP just in case.

[Dupontdon24]

Originally Posted by Blueovalman

I would use Mobil 1 75W90 gear oil since GM engineering highly recommends using it. Just make sure you change it on time though.

Don't want to sound stupid, but what is the reconmended "on time"? I've looked at the manual but can't recall seeing this. Thanks

[Blueovalman]

Originally Posted by Dupontdon24

Don't want to sound stupid, but what is the reconmended "on time"? I've looked at the manual but can't recall seeing this. Thanks

Well differential fluid in your rearend get subjected to alot of
heat and breaks down just like any other oil would over time.
Also differential fluid will get dark and dirty and needs to be changed.
What I mean by "on time" is change your differential fuild before or when
your Chevrolet dealership service department recommends that
you change your differential fluid.Rather if you take it to them
to have the service done or you perform the service yourself
and keep your receipts that's your choice.
If it were me I would do the service myself.

[happycamper]

Originally Posted by Synner

The LS in Mobil 1 stands for limited slip. Both it and RP already have the additive, some diffs just seem to like some extra. I bought the additive to mix in with the RP just in case.

With just Mobil1 75W-90 LS, my rear-end developed chatter when turning. I then added the GM friction modifier and the chatter went away within several minutes (drove in circles in an empty parking lot, as suggested by service dept).

Also, the dealer service advisor said only RP Max gear has the modifier in it. So, it would be a little cheaper, and less hassle, to just buy the RP Max gear fluid.

[Synner]

Originally Posted by happycamper

With just Mobil1 75W-90 LS, my rear-end developed chatter when turning. I then added the GM friction modifier and the chatter went away within several minutes (drove in circles in an empty parking lot, as suggested by service dept).

Also, the dealer service advisor said only RP Max gear has the modifier in it. So, it would be a little cheaper, and less hassle, to just buy the RP Max gear fluid.

Well as with most dealers, yours is an idiot. Mobil 1 has it. As I said, it's diff dependent if you'll need more with either.

[Coyotekiller]

Originally Posted by Synner

Well as with most dealers, yours is an idiot. Mobil 1 has it. As I said, it's diff dependent if you'll need more with either.

The dealer was probably referring to the Royal Purple line, not all lines in general.

[Mr_Draco]

Originally Posted by Dupontdon24

Don't want to sound stupid, but what is the reconmended "on time"? I've looked at the manual but can't recall seeing this. Thanks

I see you have a '10 so I'll post the pages they are in your manual.

Chapter 8 page 16 under new vehicle break in. After 1,500 miles it recommends to change the rear diff fluid. Chapter 10 page 5 under Every 50,000 Miles it says to change the rear diff fluid.

[The_Grinch]

Originally Posted by Coyotekiller

I'm running Royal Purple Max Gear. The max gear line has the friction modifier already added to it. I've been running mine for about two weeks now and it seems to be doing great. The dealership did my install ($45 I believe) when I took it in for oil change. If I had known it was gonna cost that much I would have done it myself on jack stands. The front of the car should be a bit higher than the rear to aid in getting old fluid out. It takes about 1-1.5 quarts to refill the rearend.

Ya, talked to my dealership and the service guy said $45 a hole said there was the main hole in the differental and then some holes that needed to be filled in the Axles. I just scratched my head, said thanks and walked away. First time I heard about filling Axle holes.

Does that make sense to any of you guys that have researched and done this?

[Blueovalman]

Originally Posted by The_Grinch

Ya, talked to my dealership and the service guy said $45 a hole said there was the main hole in the differental and then some holes that needed to be filled in the Axles. I just scratched my head, said thanks and walked away. First time I heard about filling Axle holes.

Does that make sense to any of you guys that have researched and done this?

That doesn't make sense.
I would take your differential cover off and clean out your differential
and then refill it after you reinstalled your differential cover.
You need two quarts of Mobil 1 LS 75W90 synthetic gear oil and one
bottle of the GM LS friction modifier additive.I talked to a master GM
technician today and he said you need to always add a bottle of GM LS friction modifier everytime you do your differential service.

[Coyotekiller]

Originally Posted by The_Grinch

Ya, talked to my dealership and the service guy said $45 a hole said there was the main hole in the differental and then some holes that needed to be filled in the Axles. I just scratched my head, said thanks and walked away. First time I heard about filling Axle holes.

Does that make sense to any of you guys that have researched and done this?

They charge $45 dollars cause that's what GM tells them to charge. All they have to do is unscrew a plug in the top of the diff and then another in the bottom to let the fluid out. There is no need to remove the diff cover or plug any axle holes (they should already be plug with your axles). Think your dealer is just feeding you a line of bullshit to get you to pay the $45. Bottom line if they change your diff fluid at the dealership, you are gonna pay at least $45 to get it done.

[The_Grinch]

Yep, guessing they did not want my business on doing this.

[Blueovalman]

Originally Posted by Coyotekiller

They charge $45 dollars cause that's what GM tells them to charge. All they have to do is unscrew a plug in the top of the diff and then another in the bottom to let the fluid out. There is no need to remove the diff cover or plug any axle holes (they should already be plug with your axles). Think your dealer is just feeding you a line of bullshit to get you to pay the $45. Bottom line if they change your diff fluid at the dealership, you are gonna pay at least $45 to get it done.

Most Chevrolet dealership service departments will drain your differential
by just removing your drain plugs on your differential.The reason I would
always remove your differential cover when you do your differential
service is because by the time you do the service you will have shavings
and small peices of metal in your old differential fluid and that needs
to get cleaned out by there.Then refill it with Mobil 1 synthetic LS 75W90
gear oil and one bottle of GM LS friction modifier additive.
Everytime I do my differential service once a year my differential cover always
comes off regardless of what.