I bought some Pennzoil "GEARPLUS" rear end lube a few weeks ago. (stock# 4963)

The parts counter guy said I needed the $7 limited slip addative.

On the back of the oil bottle is says "GEARPLUS 80W-90 GL5 does not need a limited-slip top treatment nor is one recommended".
I showed the fine print to the parts guy. He shruges and says I need the additive anyway.

What do you guys think?

I skipped the addative.
I've been driving it for a few weeks and everything seems fine.
No stranges noises at all.

 

The GM posi additive is a must....GM....GM is the key word here. If you dont believe me do a search on the subject..

 

if you have a clutch type posi you need the additive and the only additive i'd put in is from gm, cost me around 5 dolalrs a bottle, but i get a price break

 

This largely depends on the configuration you are running...

What Penzoil means is that if you don't add the additive
they forsee no catastrophic consequences.

However they certainly try to limit their liability to the
replacement value of their product. In other words
they will neither investigate, resolve or indemnify your
rear end in any case. Hell they may even give you a hard time
about a refund if you don't like their product.

Clutch type posi's require the friction modifier to operate
properly.

The friction modifier is a great aide in noise reduction on
straight or straighter cut gears especially during break in.

 

If you don't have any noise or stuttering around corners, you're fine.

I wouldn't recommend any Pennzoil products because of their shoddy quality practices, but they may have gotten by for you. It's also possible there was adequate friction modifier left over from the previous lube residual that you don't have a problem yet.

The additive is not necessary when you use AMSOIL Series 2000 lube because they put it in for you. The price per quart of lube may be more, but it's also synthetic to better protect your gears and bearings; and when you add the $5 or $7 for the additive to the price of the gear lube you bought, the AMSOIL isn't much (if any) more expensive.

 

The statement made on the bottle leads me to believe they have included the anti-slip addative. When they state a top treatment is not recommended, it seems like they are releasing themselves from liability if an addative is used.

I failed to mention the rear-end is a 9-bolt with cone-type clutches, if that makes any difference.

Thx for the input guys.

 

The man don't lie. I don't care what the bottle or the moron behind the parts counter says, go to a GM dealer and get a bottle of the right stuff. your clutch packs will thank you.

 

I use a GM bottle in every 9 bolt differential.

Miles
www.9bolt.com

 

Thx for all the replys.
Looks like I'll be headed off to the dealership tomorrow.