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Tech Area => General Buick Tech => Topic started by: Shimy87 on October 18 2017, 07:25:20 PM

Title: Rear end oil change
Post by: Shimy87 on October 18 2017, 07:25:20 PM
What should I refill rear with??
Title: Re: Rear end oil change
Post by: Scoobum on October 18 2017, 10:23:35 PM
I grab posi additive and gear lube from my GM dealer here in town. I've been beating on that Auburn Pro Series unit for 7 seasons...and it's still hanging in there...so I must be doing something right.
Title: Re: Rear end oil change
Post by: Scoobum on October 18 2017, 10:46:36 PM
Shimy, if the funds are there...grab a diff girdle. It's cheap insurance. I have the one from Jeremys yellow car on mine...along with his dual fan setup.
Title: Re: Rear end oil change
Post by: 1KWIKSIX on October 19 2017, 07:18:45 AM
X2 I'm with Brad .


Here's what Auburn say about oil for their differentials. ....this is also what I run in my Auburn Pro Series rear end.
Obviously you can substitute the Auburn Gear Friction Additive with the GM product.

Non-Synthetic 80w90 GL-5 oil treated with Auburn Gear friction additive, part #504102 (also known as a friction modifier). Three (3) ounces of additive will treat one quart of oil. GM or Ford limited-slip additive may be used. We do not recommend synthetic oil.
Title: Re: Rear end oil change
Post by: earlbrown on October 19 2017, 10:39:09 AM
 If you have a stock posi I like synthetic gear dope.   Don't add the whale jizz additive unless you get chatter.
Title: Re: Rear end oil change
Post by: good2win22 on October 19 2017, 12:07:28 PM
Has anyone seen an aftermarket diff unit manufacturer that recommends a synthetic? I know eaton does not recommend synthetic
Title: Re: Rear end oil change
Post by: earlbrown on October 19 2017, 02:43:48 PM
Do they not recommend it, or recommend against it?
Title: Re: Rear end oil change
Post by: gusszgs on October 19 2017, 02:50:31 PM
Just redid the clutch packs in my T. Got them from Bruce Ponti. He's been doing rear ends for yrs and said Dino 75-80/90 with Posi Gm additive
Title: Re: Rear end oil change
Post by: reality on October 19 2017, 04:05:21 PM
From what I gather synthetic will 'fall' off if the car sits any length of time.
Title: Re: Rear end oil change
Post by: good2win22 on October 19 2017, 04:41:48 PM
Do they not recommend it, or recommend against it?
I'm pretty certian eaton recommends against using synthetic
Title: Re: Rear end oil change
Post by: Scoobum on October 19 2017, 06:39:16 PM
Shimy, while you're under there ya' may as well toss a set of Moser axles in it. Only a few more minutes work. If the wife starts complaining... give 'er the choice of axles or you pissing the cash away on peelers.
Title: Re: Rear end oil change
Post by: Shimy87 on October 19 2017, 09:28:19 PM
 :icon_lol:   :cheers:
Title: Re: Rear end oil change
Post by: earlbrown on October 20 2017, 11:43:58 AM
I wonder if that recommendation is because they would sell less additive?


My stock posi chatters with dino and doesn't with fully synthetic.


Since I've got over 1/4 million miles on my stock rear end on synthetic, I think I'll ignore the advice and stick with what I've got.
Title: Re: Rear end oil change
Post by: good2win22 on October 20 2017, 02:31:05 PM
I wonder if that recommendation is because they would sell less additive?


My stock posi chatters with dino and doesn't with fully synthetic.


Since I've got over 1/4 million miles on my stock rear end on synthetic, I think I'll ignore the advice and stick with what I've got.
Earl my question was about aftermarket diff manufacturers
Title: Re: Rear end oil change
Post by: Forzfed on October 20 2017, 03:23:01 PM
Do they not recommend it, or recommend against it?

Good question.  All I know is my posi with the synthetic no longer works as good as it use to.  Sometimes I question if I even have a posi!  Sucks especially in the Truck with ice and deep snow.  It works but takes much longer to lock up. :(
Title: Re: Rear end oil change
Post by: earlbrown on October 21 2017, 02:47:24 PM
That's kinda the science behind it.

The reason you have to use the additive is to make the oil slicker so the clutches don't bite as hard.  Since synthetic is already slicker a lot of times you don't have to buy the additive.


I can't think of one reason that you'd purposely use a fluid with more vicious drag than you have to.
Title: Re: Rear end oil change
Post by: phil_long on October 23 2017, 01:01:31 PM
As I sit here never knowing it ever needed servicing. Lol. The rear end that is. Never dawned on me
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