What's the best fluid to use for the rear gears?

 

curious as to why you would want to change it. There is another thread on here where a guy just turned 250,000 miles with the stock stuff. Haven't heard of rear ends dieing. My concern is that I might get stuck with the used car that some self proclaimed expert just screwed up. I had 90 k on my 00 and it was fine. http://forums.corvetteforum.com/zerothread?id=434648


[Modified by jimman, 10:41 PM 11/20/2002]

 

I'm putting in a new rear end ;)

 

I have a lot more faith in the Automotive Engineers at GM than all the advise I get here from guys. I'd go with the standand stuff.

 

After 500 miles on my new 3.73 diff I put redline in, the gears are quite and smooth as silk. With the Redline product you don't need the additive.
I'm sure there are other good products you can use as well including OEM.
:cheers:

 

I am curious if the Redline fluid would quiet the "marbles in a can" noise down...

Patrick :cheers:

 

I've tried Redline with and without the additive, I've tried Mobil ! with and without the additive

Still chatters :cry

 

I just had my 4.10's installed at a local dealership who has done 100's of differentials. (only took this guy two hours including droping the whole tranny vs. taking a chance lowering it) - BTW: They charged me for four hours (per the books).

I put in the GL-4 (non synthetic) and the Lubrican Clutch additive based on his experience and recommendations. (He also races stock cars) He has had more noise problems and a few failures with the GL-5. (Obviously GL-5 is probably the best of the synthetics and lasts much longer than GL-4). In fact, GM told him to switch to GL-4 for his customers having noise problems.

My 4.10's are just as quite (even quieter during shifting) than my 3.42's and easier to shift. (He realigned the shifter using the neutral locking pin. It may have been slightly out of allignment from the factory.)

Just my .02 worth...

BTW - I probably would stick with GL-5 (Stock additive on my 3.42s) since I really didn't have any problems with it either. GL-5 is also 3.5 times more expensive than GL-4.

 

Mine has been changed out 4 times for an average of 10k per change :D . 3 times with stock synthetic 75w-90 gear oil and the GM friction modifier and once with Mobil One 75W-90 gear oil. The reason it has been changed so much is due to the reoccuring leaking seal problems (under warranty), which hopefully now is fixed :rolleyes: Personally after trying different fluids, I would be comfortable with stock synthetic, Mobil One, Amsoil, Redline.

One minor point, you will hear folks say that with Amsoil and Redline that do not need to add friction modifier for certain specified recommended Amsoil and Redline products already have the friction modifier in the formula. The technical glitch, if you read the fine print is that the friction modifier in Amsoil and Redline is 5%. The GM specifications, if you do the math, calls for a min of 6%, the actual value is 6.25%. (4oz of friction modifier, 4 qts x 16 oz=6.25%) So to me that is 20% light in the friction modifier dept.

 

While I agree, on a percentage basis some pre-mixed oils may appear light, in actuallity the best way to set it up and to not put it in and then add until any chatter is gone. I tend to think, based on this, that Amsoil and Redline may have too much modifier. I know a few people with it straight from the bottle who have problems spinning both tires and as a result the mixture had to be tweaked. More is not necessarily better.

 

Procedurally, if you have the time, money (if you do not DIY) inclination, and the equipment, that is one way that is described as an option. I would say that most folks % wise would probably like to "nail it "the first time if they can help it. I for one certainly found it a PITA to bring back my Z06 Vette to the dealer 5 times for the three time rear end leak problem, despite the fact that: 1. all those times were covered under warranty, i.e. free, no extra charge. 2. I didn't have to do it ( I also have all the tools and lift equipment, but still a PITA)

I did not mention that for one of the 3 changes, the use of a leak detecting dye added to the rear end differential to check for and possibly isolate the leak might have been enough to cause "chatter" The fix was to R/R the fluid and add the 4 ozs of friction modifier. Problem solved.

While off topic, a change of the ATF from conventional to synthetic certainly make the 6 speed transmission work a lot nicer, not to mention the app .5 or 1/2 mile better in mpg. Again I would be comfortable with Mobil One, Amsoil, Redline. (The stock ATF brew is not synthetic)





[Modified by ruking1, 6:11 AM 11/22/2002]

 

NO

 

I'm using a synthetic fluid from BG, it already has the friction modifier in it. So far so good, not sure of the cost, but I believe it was pretty $$. If it were my money, I would probably use the GM stuff with the friction modifier.

 

Here is info on the GM additive that I gathered from the web and emails to Redline:

Limited Slip Axle Lube Additive
The GM part # is 1052358. You should add this before putting the new fluid in the diff.
The local stealer here charges $9 for it. GMpartdirect.com shows a list of $5 but you have to buy 12 of them.

Amsoil and Redline claim that there fluids already have an additive in them. Amsoil says it both ways on there website:

AMSOIL gear oils are formulated with friction modifiers for limited slip differential applications. There is no need to add limited slip or additional additives.

AMSOIL Series 2000 Synthetic Gear Lube provides limited slip performance. Although generally not necessary, original equipment manufacturers' limited slip additives may be used in conjunction with AMSOIL Series 2000 Synthetic Gear Lube.

Redline says:

LIMITED-SLIP COMPATIBILITY Red Line Gear Oils, with the exception of the 75W90NS, already contain friction modifier required for operation in limited-slip differentials. Additional additive is not required.

I have emailed Redline and asked them if it would not hurt to add the GM additive to Redline.

Here is the reply from redline:

The 75W90 would be suitable for the limited slip in your Z06 it contains 5% friction modifier, typically what is needed to reduce the chatter from the limited slip when making a slow tight turn. Adding more friction modifier if it isn't needed reduces the lock up of the limited slip and reduces it's effectiveness, so I wouldn't add it unless it is needed due to chatter and then only just what is needed. The friction modifier isn't a lubricant but just an additive to make the fluid slipperier for chatter control. The 75W90 should be suitable right out of the bottle without the need for the additive. Thank you for your interest in Red Line Oil.

It states in the GM manual that no WOT for 300 miles after the diff fluid is changed.

 

"The GM part # is 1052358. You should add this before putting the new fluid in the diff.
The local stealer here charges $9 for it. GMpartdirect.com shows a list of $5 but you have to buy 12 of them"

The brand "Sta Lube" has a friction modifier that mets the GM P/N specification. I bought it last at $5.99 per 4 oz tube at the local auto chain store.

Just to add to what you have said about Redline. Redline also sells a stand alone friction modifier. "

Some possible uses?:

1. Friction modifier of 5% in their own products is not enough
2. As mentioned by another poster, to follow the procedure of putting "just enough" for their own particular application.
3. To be the friction modifier of choice when you add other than Redline gear oils and have the requirement for a friction modifier.
4. A marketing trick. If you do the math, and have it down to say Mobil One plus friction modifier and or Redline, buying Redline is actually cheaper (but not by much) than Mobil One AND friction modifier. So if you decide to go with Redline AND the 5%friction modifer solution is not enough viola, they offer additional friction modifier!!! Of course by this time you will see that you have just spent way more!!

Incidently, GMblack3 has done a really neat visual and instructional procedure on how to change the rear differential gear oil. After seeing it, I was motivated to DIY !!

Thanks GMblack3 !!!


The down side? If you had smell a vision, the old stuff STINKS!!! :eek:




[Modified by ruking1, 9:19 AM 11/23/2002]

 

Here is the new link for tranny and diff fluid changes:
http://www.woosch.com/tranny_diff_fluid_change.htm

Thanks to woosch for hosting this info.
:cool:


[Modified by gmblack3, 11:21 AM 11/25/2002]

 

Amsoil, hands down!

 

I wonder who follows that rule... I know I sure don't.

 

So just buy new. That way you only get stuck with such great features as "column lock", "gas gauge drops to empty", "excessive oil consumption", and, my favorite: "clutch won't return". :lol:


[Modified by 6Speeder, 3:54 PM 11/23/2002]

 

I use redline with no extra additive added beyond what is included in the fluid. If you take your car to any DE events, all fluids get hot, which stresses them over time. Prudent practice is to change the fluid periodically. I did the same thing with the tranny fluid--redline.