GL-4 vs GL-5 4 speed gear oil
08-09-2022, 01:05 PM
#1
Burning Brakes
Thread Starter
GL-4 vs GL-5 4 speed gear oil
Ok so I want to change gear oil in my 75 L48 4 speed .. a little confuse on what I should use..my owners manual says 80/90W GL-5 non Synthetic… However doing some research I am reading some C3 owners are saying you should use the GL-4 Synthetic… Any opinions would be appreciated… Also what is the gear oil capacity in the gearbox , and what brand oil are best thanks
08-09-2022, 03:03 PM
#2
Melting Slicks
Get two quarts of Lucas 85W140 non-synthetic and two bottles of Delco 10-4003 additive.
Unless you are shock loading the differential (e.g. drag racing), a GL4 spec is all you need.
Unless you are shock loading the differential (e.g. drag racing), a GL4 spec is all you need.
Last edited by 69L88; 08-09-2022 at 11:11 PM.
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08-09-2022, 03:14 PM
#3
Melting Slicks
4 speed differential - ya!!
Non-synthetic is recommended because synthetic is allegedly tough on the brass components. Having said that I have been running Mobil1 for many years and I love how it shifts and how smooth it is!
No additive for the 4 speed.
Non-synthetic is recommended because synthetic is allegedly tough on the brass components. Having said that I have been running Mobil1 for many years and I love how it shifts and how smooth it is!
No additive for the 4 speed.
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08-09-2022, 05:07 PM
#4
Le Mans Master
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08-09-2022, 05:57 PM
#5
Racer
I'm using GL-4 80/90 classic gear oil in my 66 and 72 as per the owners manual . It is non synthetic, due to the previously mentioned effect synthetic has on brass parts. Brand is Penn-Grade 1. I have to have the local distributor order it for me as he does not normally stock it. He usually has it next day, sometimes the second day. My 72 takes about 1 1/2 quarts, the 66 a little less.
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grady white (08-09-2022)
08-09-2022, 08:10 PM
#6
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