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#1 |
Registered User
Join Date: Mar 2015
Location: Yorkton, saskatchewan
Posts: 4
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1967 GMC 930 Manual Trans Fluid?
The manual calls for “straight mineral oil gear lubricant”. I am not finding any locally. Does anyone know if there is a modern replacement for this?
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#2 |
Registered User
Join Date: Dec 2017
Location: Elkhart, Texas
Posts: 1,723
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Re: 1967 GMC 930 Manual Trans Fluid?
My Chevrolet Manual says SAE 80 or SAE 90 GR5.... Same for all manual transmissions.
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#3 | |
Senior Member
![]() Join Date: Feb 2002
Location: Tucson, AZ USA
Posts: 7,286
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Re: 1967 GMC 930 Manual Trans Fluid?
Quote:
Also if you have an SM 420 transmission, with brass synchros, you want service GL-4. GL-5 has additives for limited slip [Positraction] but these additives attack brass synchros. ''Mineral Oil'' refers to natural petroleum oil, not Synthetic. In 1967 synthetic lubricants were rare. Much has progressed in this field since then, but if you want to go by the book, avoid them.
__________________
Every 25 years I like to rebuild that 292, whether it needs it or not. |
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#4 |
Registered User
Join Date: Mar 2015
Location: Yorkton, saskatchewan
Posts: 4
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Re: 1967 GMC 930 Manual Trans Fluid?
My dad was doing some reading and came across something that said to make sure there is no sulfer in it…?
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#5 |
All stock and staying that way
![]() Join Date: Jul 2003
Location: Elkland, PA
Posts: 1,498
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GL-4 80w90
__________________
1970 K/5 Blazer CST 4WD, Bronze, 93k ACT. miles, 350, 4 speed, positraction, 16.5" x 8.25" wheel option, tilt, tach, vacuum, AM/FM, manual throttle...Dad ordered and purchased new 4/70. Currently frame off restoration in progress... ![]() 1972 Cheyenne Super 20 2WD, DK Blue/White, 90K ACT. miles, 402, TH400, 4.10 open, tilt, tach, vacuum, A/C, AM/FM, manual throttle.. A mostly original paint never rusted Texas survivor... ![]() 2017 Sierra 1500 SLT 4WD, Black, 41k miles, 5.3, 6L80E, 3.42 LS, 20" polished wheels, everything but moonroof and 6.2... 2019 Canyon SLT 4WD, White, 60k miles, 3.6, 8L45, 3.23 LS, 18" wheels |
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#6 |
Registered User
Join Date: Mar 2015
Location: Yorkton, saskatchewan
Posts: 4
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Re: 1967 GMC 930 Manual Trans Fluid?
Looks like this is what I am looking for. My dad did some more checking found someone that also recommends the GL-4. Most is GL-5 and not what the transmission wants.
Here is a quote from Penngrade oil.."PENNGRADE 1® CLASSIC GL-4 GEAR OIL SAE 80W-90 PennGrade 1® Multi-Purpose ‘Classic’ Gear Oil GL-4 SAE 80W-90 is a specially blended using high quality premium mineral base stocks and select additive technologies. It is designed to be used with “yellow” metallurgy (brass, bronze, copper) and other ‘soft’ metals used in synchronizers, bushings, thrust washers and other components typically found in classic manual transmissions and transaxles. In applications specifying API GL-4 quality lubricants, use of API GL-5 lubricants with higher extreme pressure additive activity/concentration can damage these ‘soft’ metal components." This makes perfect sense and I am confident now to replace the fluid with a GL-4. Thanks! |
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#7 |
Senior Member
![]() Join Date: Feb 2002
Location: Tucson, AZ USA
Posts: 7,286
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Re: 1967 GMC 930 Manual Trans Fluid?
Sounds good. Why was GM leery of multi viscosity 57 years ago?
They call for ''Straight'' oil.
__________________
Every 25 years I like to rebuild that 292, whether it needs it or not. |
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#8 |
Senior Member
![]() Join Date: Mar 2003
Location: Colfax-California
Posts: 8,553
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Re: 1967 GMC 930 Manual Trans Fluid?
Right there. Have found out a couple of times when a customer has had their vehicle serviced elsewhere and then starts experiencing shifting issues. Drain and fill with GL-4. The GL-5 is too slippery for the brass rings to grab the gear and slow it down
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#9 |
Registered User
Join Date: Apr 2014
Location: California
Posts: 951
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Re: 1967 GMC 930 Manual Trans Fluid?
Where do you pick up your GL-4, mech?
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#10 |
Senior Member
![]() Join Date: Feb 2002
Location: Tucson, AZ USA
Posts: 7,286
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Re: 1967 GMC 930 Manual Trans Fluid?
Supertrooper: What transmision do you have?
__________________
Every 25 years I like to rebuild that 292, whether it needs it or not. |
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#11 |
All stock and staying that way
![]() Join Date: Jul 2003
Location: Elkland, PA
Posts: 1,498
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I just picked up a bottle of Valvoline GL-4 at my local Carquest. It was $13.
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__________________
1970 K/5 Blazer CST 4WD, Bronze, 93k ACT. miles, 350, 4 speed, positraction, 16.5" x 8.25" wheel option, tilt, tach, vacuum, AM/FM, manual throttle...Dad ordered and purchased new 4/70. Currently frame off restoration in progress... ![]() 1972 Cheyenne Super 20 2WD, DK Blue/White, 90K ACT. miles, 402, TH400, 4.10 open, tilt, tach, vacuum, A/C, AM/FM, manual throttle.. A mostly original paint never rusted Texas survivor... ![]() 2017 Sierra 1500 SLT 4WD, Black, 41k miles, 5.3, 6L80E, 3.42 LS, 20" polished wheels, everything but moonroof and 6.2... 2019 Canyon SLT 4WD, White, 60k miles, 3.6, 8L45, 3.23 LS, 18" wheels |
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