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Apr 1, 2008 | 02:20 PM

Rick B.

Thread Starter

Heel & Toe

Joined: Dec 2006

Posts: 23

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From: Trezevant TN

motor oil

What brand and viscosity oil is recommended by GM for a 1971? Also the previous owner said he used straight 30 wt. Do you guys have any experience with switching viscosities? What's the best product to use to try and help a rear main seal leak?

Apr 1, 2008 | 03:13 PM

Jims79

Safety Car

Joined: Dec 2004

Posts: 4,876

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From: Jersey Shore Exit 98

Quote:

Originally Posted by Rick B.

Depends on the miles on the motor. 10w40 high mileage oil is fine, a stop leak could help the main but if the seal is shot then nothing is going to repair it . It maybe time to replace it. I run 20w50 and add a good oil additive like Lucas to help on starts after its been sitting for a while.

Apr 1, 2008 | 03:14 PM

7T1vette

Team Owner

Joined: Jan 2006

Posts: 37,637

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From: Crossville TN

There is no 'oil' that will help you get the rear seal to stop leaking. There may be some [short-term] additives that are made to reduce gasket/seal leaks, but I wouldn't put them in my engine. If the leak is significant, just have it repaired (and put in a new Fel-pro oil pan gasket at the same time). A decent mechanic can replace the rear seal without doing any major disassembly of the engine.

Apr 1, 2008 | 08:06 PM

dmayhew

Drifting

Joined: Oct 2007

Posts: 1,254

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From: Brown Summit North Carolina

I do not believe GM would have suggested a brand name of oil.

As for viscosity , that depends on the climate you drive in and the way you drive the car.

The 30w seemed to have worked for the previous owner

David

Apr 1, 2008 | 08:55 PM

auctionman256

Instructor

Joined: Dec 2007

Posts: 147

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From: GADSDEN ALABAMA

true

Apr 2, 2008 | 01:08 AM

thrilher

Racer

Joined: Sep 2006

Posts: 484

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From: McComb Ms.

i would go with Shell 30wt.It comes in gallons and if not on the shelf they usually have it behind counter at most parts houses.if you don't see that weight, just ask.