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Topic: Preferred Tranny & Rear End Oil

in Forum: C3 Driveline Components


Preferred Tranny & Rear End Oil

Posted: 3/15/05 3:14pm Message 1 of 8
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METAIRIE, LA - USA
Joined: 12/25/2004
Posts: 17
Vette(s): 2000 Hardtop 1991 Zr1 1970 LS5 Coupe
What is our favorite gear oil for M21 transmission in 1970 454? Also what is favorite rear end oil for posi rear end same vehicle?


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Preferred Tranny & Rear End Oil

Posted: 3/15/05 5:53pm Message 2 of 8
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Marion, IA - USA
Joined: 4/24/2004
Posts: 317
Vette(s): 1969 Corvette Stingray Convertible. Just bought it from my uncle who owned it since 1971. Fathom green, green interior. 350/300, T400.

I don't know about the tranny since mine's an auto, but I'd recommend synthetic for the rear, that is if you have all new seals. Supposed to be good for a few horses and mileage.

 

Matt




Preferred Tranny & Rear End Oil

Posted: 3/15/05 8:11pm Message 3 of 8
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Duncanville, TX - USA
Joined: 11/8/2003
Posts: 20219
Vette(s): #1-1974 L-48 4spd Cp Med Red Metallic/Black deluxe int w/AC/tilt/tele./p/w-p/b/ Am-Fm/map light National/Regional/Chapter NCRS "Top Flight" #2-1985 Bright Red/Carmine Cp.L-98/auto Member: NCRS, NCRS Texas, Corvette Legends of Texas
Absolutly go with the synthetic for both. Less heat, less wear. Be prepared, tho, for small leaks to appear, unless you have new seals installed. If you don't need the hassle, use a regular 80/90 wt. gear oil in both, with the posi additive in the diff., if you have a posi, which you should.


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Preferred Tranny & Rear End Oil

Posted: 3/16/05 3:57am Message 4 of 8
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Miramar, FL - USA
Joined: 3/16/2004
Posts: 672
Vette(s): 1972 coupe/350 cid/mild cam/4 spd/20 ft. paint (looks perfect from 20 ft.), but it sure runs nice.

Went with Red Line gear oil for the rear...make sure it's the one with the posi fluid in it already. My M21 leaks some so I went with good 'ole Valvoline (I believe it's 85w-90). The smaller molecules of the synths flow through the cracks easier....and at $7.95 a quart. My $0.02 worth.

JR

P.S. How's that for name-dropping?

jredding38427.1674305556


Preferred Tranny & Rear End Oil

Posted: 3/16/05 7:09am Message 5 of 8
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METAIRIE, LA - USA
Joined: 12/25/2004
Posts: 17
Vette(s): 2000 Hardtop 1991 Zr1 1970 LS5 Coupe
Thanks for the feedback. The rear end is pretty tight - looks like it's been reworked from the way it has been sealed, but the M21 like all the other old trannies has a few leaks here and there, so I will try everyone's advice.


Preferred Tranny & Rear End Oil

Posted: 3/16/05 8:36am Message 6 of 8
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Miramar, FL - USA
Joined: 3/16/2004
Posts: 672
Vette(s): 1972 coupe/350 cid/mild cam/4 spd/20 ft. paint (looks perfect from 20 ft.), but it sure runs nice.

Nothing like a tight rear-end (sorry,couldn't resist).......My diff 's ok, too, that's why I have the synth in it. I asked the Red Line tech guys if additional limited-slip fliud was needed for proper functioning, they said a resounding NO. No chattering or clunking. Now, the oil marked NS is a different story. That has no posi fluid in it. Hope all this helps.

JR

jredding38427.3640625


Preferred Tranny & Rear End Oil

Posted: 3/16/05 12:35pm Message 7 of 8
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CUYAHOGA FALLS, OH - USA
Joined: 12/2/2003
Posts: 6424
Vette(s): 1975 C3 Red, T-Tops, Black Interior. All I need is time and money! Getting there!
I can see using dino or synth in the back of the car, but I have never oiled my rear end.  I think it would make me slid off my chair.   (sorry)


Preferred Tranny & Rear End Oil

Posted: 3/16/05 1:16pm Message 8 of 8
Former Member
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Miramar, FL - USA
Joined: 3/16/2004
Posts: 672
Vette(s): 1972 coupe/350 cid/mild cam/4 spd/20 ft. paint (looks perfect from 20 ft.), but it sure runs nice.

.......this might be getting out of control.

JR

jredding38427.5557060185


in Forum: C3 Driveline Components


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