Gears & Axles - Just installed royal purple fluid and now my rear is noisy :/

So what fluid should I use? I also added the additive and some royal purple and my rear is making a whine noise well under slight acceleration .. Also makes a lil noise when I make sharp turns , now my question is , is it the fluid I am using ? Or is it my rear ? This all started when I first changed my fluid to royal purple.. I only used royal purple because that's all they had on base :/ .. Please any advice would be awesome !! Thanks !!

So what fluid should I use? I also added the additive and some royal purple and my rear is making a whine noise well under slight acceleration .. Also makes a lil noise when I make sharp turns , now my question is , is it the fluid I am using ? Or is it my rear ? This all started when I first changed my fluid to royal purple.. I only used royal purple because that's all they had on base :/ .. Please any advice would be awesome !! Thanks !!

It's the fluid. My buddy changed his with Royal Purple and his did the same thing. Switched back to Auto Zone brand 80/90 and was quiet again. What diff do you have in it?

What's the mileage on the rear?

Depending on the posi you may not need the additive. It can cause the posi to slip too much and this could be your noise in the turns. I never used the additive with royal purple with my auburn and it never gave me any problems. Under light acceleration it could simply be the pinion bearings but to know for sure you should check all the specs i.e proper torque, back lash, bearing life etc.

Car has 42k miles and yeah before when I had my rear end rebuilt (bearings) I forgot what fluid I used but it was not this loud and I know it was not royal purple .. My car is a 02 ss how can I find out what exactly I have in my rear? I have 373 motive gears and a trick flow girdle .. What fluid should I use? And will I need the additive ? Please let me know because I do not feel comfortable using my car making that noise :/ shit bothers me big time ..

Car has 42k miles and yeah before when I had my rear end rebuilt (bearings) I forgot what fluid I used but it was not this loud and I know it was not royal purple .. My car is a 02 ss how can I find out what exactly I have in my rear? I have 373 motive gears and a trick flow girdle .. What fluid should I use? And will I need the additive ? Please let me know because I do not feel comfortable using my car making that noise :/ shit bothers me big time ..

You would have to just open it up and look. I use 80/90 in mine. You need lsd additive if it is a clutch unit. If it is a gear unit like a trutrac ect you wont need additive.

Ok .. I will check it out.. What brand of fluid ? Sorry I have to order it from base so I need the info .. Because on base all they got is RP:/

Ok .. I will check it out.. What brand of fluid ? Sorry I have to order it from base so I need the info .. Because on base all they got is RP:/

I use Valvoline but any conventional gear oil should be fine.

Gotcha , thanks .. And 80/90 will work?

x2 valvoline syn blend, great stuff royal purple way over rated i personally wont use it in anything

Gotcha , thanks .. And 80/90 will work?

That's what I use. Most manufacturers will tell you just to use conventional and that's what I have always used. Good luck.

Conventional FTW!!!


Tis what I used on my 99 Z28






No problems. :chug:

I use royal purple in my diff (stock 10-bolt), royal purple has the LSD additive in it already and not needed. conventional oil or synthetic oil needs the additive. my rear has been howling since the so called "rebuild" this guy ripped me off for. so i couldnt tell you if it was oil or not. but its in there and still whining away! we will see when i put new tires on if the diff hold up or not. i would say its not the oil though IMO. hard to find someone who actually knows diff specs and knows how to build them.

Reg gear oil with additive, no need for that fancy stuff.

I changed mine to synthetic when I installed the T/A cover with the supports and now it makes noise. Car has about 80k on it. I used the additive as well. I think it is due to the syn being a lighter fluid. I dont really think it is an issue but I could be wrong on that.

So what fluid should I use? I also added the additive and some royal purple and my rear is making a whine noise well under slight acceleration .. Also makes a lil noise when I make sharp turns , now my question is , is it the fluid I am using ? Or is it my rear ? This all started when I first changed my fluid to royal purple.. I only used royal purple because that's all they had on base :/ .. Please any advice would be awesome !! Thanks !!
Camaroboy ,
You have a couple options:
1.Go to Trost or ATU and look for gear oil there (Liquid Moly, Valvoline etc)
2. Opel dealer that services GM products.

It is a little more expensive but it is on hand .
FWIW the factory fill on the axle is syn gear oil.

If your German is not that good just be polite and ask in english.

Thanks everyone..
Hey Roy, Opel dealerships have the fluid? Yeah I hate ordering my additive through eBay costs almost 30$ for just that :( haha .. I was just gonna have a family member or a friend get the stuff state side and ship it .. But have them wrap it like crazy .. Idk ..

That is Opel dealers that sell American cars. The ones that sell American cars have the GM logo on their sign and show room will have a couple of GM cars in it.

Drive it down to Schweinfurt, and I'll check it out for you, if need be.

Hey z28 do you got that 10sec z28? The one at bittburg ? And I would but your almost 4 hours away :/

http://www.autozone.com/autozone/accessories/Valvoline-1-qt-80W-90-Durablend-synthetic-gear-oil/_/N-25t1?itemIdentifier=25555_0_0_

That one? Or

This one ?
http://www.autozone.com/autozone/accessories/Valvoline-1-qt-80W-90-high-performance-gear-oil/_/N-25t1?itemIdentifier=232566_0_0_

Anyone :)?

Try this

Liqui Moly GL5 85w90 (http://www.liqui-moly.de/liquimoly/produktdb.nsf/id/en_1410.html?OpenDocument&land=GB&voilalang=e&voiladb=web.nsf)

The stuff you showed will work but has a postal restriction for APO.

Hey z28 do you got that 10sec z28? The one at bittburg ? And I would but your almost 4 hours away :/

No but I've seen that one that you're talking about, before.

Back to the question about which 80-90 to use, I wouldn't use synthetic, IMO, RP is synthetic and your gears are whining. Have you looked in Esso gas stations or at the Auto Shops on post (assuming you're a GI).

Esso stations no, and the care care center here only sells royal purple :/ idk why but yeah .. The auto hobby shop I have not checked there yet .. I will call tomorrow and ask them

I looked at my car care center today (in Schweinfurt) and we have 75-90 non synthetic. about 5 bottles... FYI.

Find any 80-90 gear oil and run an additive. Keep the fancy oils for the engine where the bearings need the "less friction" stuff.

I am no longer a believer in synthetic gear oil for a rear end.
Last year I went to the strip and after 5 runs my 3.90 Motive ring and pinion in my nine inch with 2K miles was totally destroyed. The gears prior to going to the track were setup correctly and were 99% silent and working very well. I was running synthetic royal purple lube IIRC and no it was not low on fluid.

As soon as I hit the street to return home they were screaming like a banshee on acceleration only and vibrating like OMG. Went around a corner and they were clunking something awful too.

Got home and pulled the gearcase and found that the teeth on the R&P were severely worn down and the housing was full over silver sludge to the point where there was .040" of backlash. Original setting was .010" IIRC. Nothing moved in the gear case, this was caused by heat and friction.

There is no reason these gears should have failed like they did so I blamed it on the synthetic lube after surfing the net and finding that a few others have had the same problem. I found a 50/50 split on those who swore by synthetic and those who would never put it in the rearend and go racing.

I now have new gears and am running standard 70/90 gear oil and all is well, but I have not been back to the track since.

My 2 cents.

Ok I got the fluid and additive .. Now here is a dumb question how can I drain it and fill it my self? I have a trick flow girdle cover and it has the drain plug in the middle , so do I drain it from there or another area ? It's my first time so sorry for the newb question.. But please I plan on doing this tomorrow so I need the help now .. Thanks

Yes pull that bottom most plug and let it all drain. Reinstall that plug and pull the upper plug (should be right in the middle and probably hard to get to because the sway bar) and fill it until fluid starts to seep out. Reinstall plug. Drive like hell!

So by pulling that middle plug That will fully drain it? Even though it's in the middle? Sorry again just making sure I know what I am doing

The plug in the middle is not the drain, it is the fill hole.

If there is no drain plug at the bottom, then remove the cover to drain it.