Discussion Forum - Northstar Chevelle Club

Synethic lube is great in modern vehicles made for it, but from my experience, the older cars didn't have the precise tolerances to keep it inside. If it is the chrome cover leaking, you may want to consider replacing it with a real cover. The chrome ones are much thinner and bend too easily to provide a tight seal. Also, use a gasket, not just a sealer. If it is the front seal leaking, I would seriously think about changing out the syn for oil based lube.

Ron,

I use Valvoline High Performance 80W-90 gear oil for limited slip differentials plus I add 6 oz of Champion Limited Slip Differential Axle Additive Concentrate.

Posi additive should also still be available from your local dealer as part number 88900330 (updated part number from the old # 1052358) for about $13 or less.

Stan, when I talked to Ron on Saturday, he said he lived in either Egan or Apple Valley.  There all the same to me, so I can't remember.  But maybe he is close to you or Kevin.

I grew up in Burnsville on the northeast tip of it, and they're all the same to me too. Wasn't anything to cruise over to Eagan for something, then down to Apple Valley for something else and back through B'ville to get home.

66 RAT wrote:

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Thanks for all the replies. I do appreciate the assistance. But now a follow-up question:

Is it OK to mix synthetic gear lube with oil-based lube? Since some engine oils are a mix of syn/oil, I'm assuming it's OK to do the same with rear end lube. It's not leaking enough where I'm going to do anything with it at this point. Instead, I'm just going to add whatever is needed.

Jim, I didn't see you later on Saturday in Hastings so I'm assuming that you decided to head for home after the car show. I got a little sunburn after being out in the sun all afternoon.

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NO, top it off with syn...

 

jim larson wrote:

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Ron, not clear on your question.  Is there non-syn oil in there or is there syn oil in there now?  Do you know for sure?  I see from your initial post that you thought the previous owner said he had put syn oil in there.  I would not rely on an unverfied statement.    

 

Where is the leak, in the cover or is it leaking from the front of the carrier by the pinion flange seal.  How bad is it.  I guess if it is low and I was unsure of the oil , then I would fix the leak and put in all new oil.

What rear do you have?  Is it a 10 bolt or did a previous owner put in a 12 bolt or something else like a ford 9" built for a chevelle.  Your car looked to be built up quite a bit, so I would think the 10 bolt would be gone.

I think there is a good shop in Lakeville that some of the guys have used for real axel work.  You might want to consider that.

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 I agree with Jim, dont just top it off under speculation. Personally, I would pull the cover off so it drains out and reseal the cover and put in all new stuff that you know for sure is what you need. When filling the diff, always put in the additive first so its in there already, then fill the rest with the plug off using the gear oil until it stops trickling out. Its then filled up.

Sounds like a "tech-session" at a meeting in the future!

Determine the cause of the leak (cover or pinion). Cover = easy, Pinion = PITA.

1st guess would be the diff cover, and the culprit being (my personal nemesis) silicone sealant - don't ask - or a cheapazz chrome cover, or a combo of both.

You're only out around $50 for a gasket, some additive, and few bottles of lube. (notice I didn't mention anywhere in there silicone sealant...)

If it's the pinion seal it's a bit of a job, but not impossible for a DIY'r. Add about $10 to the above procedure for a seal. The nut-buster is (literally) the nut on the pinion gear shaft - cracking it loose and then re-torquing it back to the position it was at.

66 RAT wrote:

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Once again, THANK YOU to all who responded. I'll have to admit that I did not think I would get this kind of assistance from so many people.

UPDATE: I've talked to the previous owner about what kind of oil he used in the differential. With the leak no worse than it is I'm going to just add some lube and let it go at that until I take the time to deal with it properly.

An additional THANK YOU to Scott Parkhurst who offered some of his Royal Purple. I may buy it from you when I do (or have done if it's the seal) the repair. (I've looked under the rear but cannot see whether it's from the cover gasket or the pinion seal --- I'll have to jack it up for a closer look.)

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On another topic, I just tried to start a new thread and got this message: "Your message has been flagged as potential spam and needs to be approved by an administrator before it will appear on the forum." The other two threads I started went through with no problem. Any idea why this occurred? Actually, I tried more than once so the administrator will probably see a couple copies of my post.

-- Edited by 66 RAT on Thursday 2nd of August 2012 03:09:03 PM

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Did you try to post from a different computer than the other threads ? 

 

John D wrote:

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(my personal nemesis) silicone sealant 

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Have you tried Permatex "Right Stuff"?

A lot of Model T guys swear by it, and if it can keep a Model T from leaking oil, it must be good. 

I haven't tried it myself yet though...

Derek69SS wrote:

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John D wrote:

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(my personal nemesis) silicone sealant 

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Have you tried Permatex "Right Stuff"?

A lot of Model T guys swear by it, and if it can keep a Model T from leaking oil, it must be good. 

I haven't tried it myself yet though...

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 Right Stuff is fantastic. It's not like silicone. If you have to remove a part that has it on it you need to first cut the Right Stuff.

Derek69SS wrote:

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John D wrote:

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(my personal nemesis) silicone sealant 

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Have you tried Permatex "Right Stuff"?

A lot of Model T guys swear by it, and if it can keep a Model T from leaking oil, it must be good. 

I haven't tried it myself yet though...

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After working as an auto tech the last 20 years, I swear by that stuff too.

RTV is like Bondo, or body filler, it gets a bad name because people are consistently using it the wrong way, RTV most certainly can be used as a gasket maker (says so right on the package).

Case in point. In the Chrysler automatics, Mopar wasnt allowing any techs to use a gasket on the 1990's through mid 00 vehicles like the Caravan and models like the Town & Country and Voyager when a leak was determined to be coming from the pan. Which was a common issue with the mopar AT. They wanted you to put on a bead of RTV and allow it to set up and install it. Ive done so many of those and never seen one come back leaking again, nor did I see any come back from the other techs doing the same repair I worked with.

Why did so many GM trucks in the mid 90s Vortech have intake manifold leaks? 90% of the time it was because of the dang end rail gaskets GM used and they leaked right out the ends of the block. Every intake job I ever did was because the end seal gaskets were leaking down the front or back of the block. What was the recommended repair along with a new intake gasket kit? Running a bead of silicone to bridge the gap between the lower intake manifold and the block. Similiar to what one would do on a classic SBC or BBC. No more leaks after that ever again, and best of all for a mechanic, no come backs. Did this job on my 97 Tahoe back in 2005 or 06 and its still clean and leak free to this day.