Transmission fluid change

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Dec 3, 2021 | 07:22 AM

Mspangler

Thread Starter

4wd Low

Joined: Nov 2021

Posts: 11

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Transmission fluid change

So I was going to change the transmission fluid in my 4 speed 70s truck transmission because it had been sitting for a while, but my dad said not to drain it because it can mess with how the clutch works or something along those lines. I’ve never heard of such thing.

Dec 3, 2021 | 09:26 PM

Mark Kovalsky

Frmr Ford Trans Engr

Joined: Aug 1999

Posts: 24,739

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From: SE Florida

Sorry, your dad has no idea what he's talking about.

Dec 3, 2021 | 10:48 PM

Jimmy's Pilot Service

Laughing Gas

Joined: Nov 2020

Posts: 994

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From: Republic of Texas

Sorry but that is along the line of:
never change oil and filters for the engine.....
never change the gear oil in the diffs either.
and for sure never grease the fittings.

Dec 4, 2021 | 07:40 AM

JWA

Fleet Owner

Joined: Aug 2010

Posts: 21,255

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From: Reynoldsburg, Ohio

Quote:

Originally Posted by Mspangler

Is this transmission an automatic or standard shift? If its an automatic NOT changing the fluid will definitely "mess with how the clutch works..........."-----guaranteed!

Dec 4, 2021 | 11:27 PM

Mark Kovalsky

Frmr Ford Trans Engr

Joined: Aug 1999

Posts: 24,739

Likes: 2,669

From: SE Florida

I don't remember any four speed automatics in the 70's, so this has to be a manual trans.

The oil never touches the clutch in a manual transmission, so there is no way changing the oil could affect the clutch.

Dec 7, 2021 | 06:50 AM

DaveMcLain

Cargo Master

Joined: Oct 2020

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He's probably thinking of the synchronizers in the transmission. Those ARE sensitive to the type of lubricant that's used and some transmissions will not shift very well with the wrong type of gear lube.