74 transmission fluid change
Thread Starter
4th Gear
Joined: Mar 2017
Posts: 4
Likes: 0
From: Atlanta GA
74 transmission fluid change
Sorry if this has been addressed but i searched and did not find anything.
Anywho, I picked up a 74 350ci 4-speed manual recently and have looked around for details regarding changing the transmission fluid with only some luck.
Can someone help out a newbie here? I haven't jacked up the car yet but I assume there is a drain plug and a fill plug. Is it as simple as that?
And what kind of fluid do you recommend? The original manual says SAE 80 but what is recommended in 2017?
I appreciate any help.
MikeD.
Anywho, I picked up a 74 350ci 4-speed manual recently and have looked around for details regarding changing the transmission fluid with only some luck.
Can someone help out a newbie here? I haven't jacked up the car yet but I assume there is a drain plug and a fill plug. Is it as simple as that?
And what kind of fluid do you recommend? The original manual says SAE 80 but what is recommended in 2017?
I appreciate any help.
MikeD.
Thread Starter
4th Gear
Joined: Mar 2017
Posts: 4
Likes: 0
From: Atlanta GA
Thread Starter
4th Gear
Joined: Mar 2017
Posts: 4
Likes: 0
From: Atlanta GA
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Pro
Joined: Oct 2015
Posts: 651
Likes: 45
From: Raleigh area, NC
They are all square on my '75, I could not get the drain plug off so had to pump it out painfully through the fill. Is on right side on mine.
Also did the rear also that had no drain, removed right rear wheel for access. I used Mobil 1 with LSD additive, so far no complaints.
Also did the rear also that had no drain, removed right rear wheel for access. I used Mobil 1 with LSD additive, so far no complaints.
Le Mans Master
Joined: Oct 2005
Posts: 6,247
Likes: 471
From: Glen Allen, VA
Yes, 8 point sockets are the secret trick on the square plugs. That's what I had to use to get the fill plug off of my trans, as a open ended wrench did give enough leverage. I used the 8 pt socket with a long handle ratchet.
Le Mans Master
Joined: Oct 2007
Posts: 7,454
Likes: 977
From: RI, Now Franklin/Nashville TN
gmheritagecenter.com
https://www.gmheritagecenter.com/doc...t-Corvette.pdf
lists the gear oil for the manual tranny as GL-5 (ML-L-2105B) which is GL5. Use the GL-5 gear oil, preferably a synthetic, which are far superior to conventional gear oil...synthetics did not exit in 1974 and you will not see a recommendation from GM for them since they were not around then. As long as it is GL5 you are good.
BTW-I bought into the GL4 recommendation for the manual tranny's without checking gmheritagecenter.com and currently have Redline GL4 in the tranny and just checked the reference for 1978 Corvettes when researching your question and guess what? My 78 also calls for GL5 which I used for years until the switch 2 years ago to the Redline synthetic GL4. Back to GL5 synthetic Mobil 1 75W-90 when I get a chance.
https://www.gmheritagecenter.com/doc...t-Corvette.pdf
lists the gear oil for the manual tranny as GL-5 (ML-L-2105B) which is GL5. Use the GL-5 gear oil, preferably a synthetic, which are far superior to conventional gear oil...synthetics did not exit in 1974 and you will not see a recommendation from GM for them since they were not around then. As long as it is GL5 you are good.
BTW-I bought into the GL4 recommendation for the manual tranny's without checking gmheritagecenter.com and currently have Redline GL4 in the tranny and just checked the reference for 1978 Corvettes when researching your question and guess what? My 78 also calls for GL5 which I used for years until the switch 2 years ago to the Redline synthetic GL4. Back to GL5 synthetic Mobil 1 75W-90 when I get a chance.
Melting Slicks
Joined: Jul 2009
Posts: 2,091
Likes: 40
i really see reason to drain it , generally for street driving it lasts a very very long time ...but can slowly leak out drop by drop over decades. just stick your finger in the fill hole see it it is low ..add till your finger touches the oil ...add a high quality tranny oil for old school transmission . i used Classic trans type Redline brand in my Z28 350, because i had it rebuilt . The auto parts store had to order it. most of that cheap stuff is for modern cars with plastic parts . If you add any in .....use the correct lube .
don't make up work ...
don't make up work ...
Last edited by LS4 PILOT; May 25, 2017 at 05:16 PM.