One synthetic for everything?

[Ron77]

Since synthetic gear oil flows easier (or least that's my perception) what would my chances be of an one size fits all for tranny/transfer and diff's using a 70's/80's-140 synthetic EP gear oil? Would I get get lubrication around the shafts and bearings in the tranny/transfer cases? The book calls for 80-90 oil. Thanks, Ron.

 

[TimVipond]

Gear lubes are formulated differently for different specs. Some equipment require GL-4, others GL-5. Some require other specs other than just viscosity. Some are formulated for trucks, others for marine.

Amsoil makes an excellent 75W90 Severe Gear Lube. I probably sell more of it than any other gear lube as it meets requirements for most motorcycle transmissions, final drives, ATV gear boxes, car and truck front and rear differentials, transmissions, transfer cases and provides excellent extended oil change intervals and fuel mileage. Let us know the equiment and gear oil specifications and we might be able to find your one size fits all gear oil.

 

[ConfederateTyrant]

Tim covered that pretty well. Most manual transmissions require GL-4 or GL-5 gear oils, and differentials require GL-5 gear oils. Based on experiences, GL-5 gear oils in a transmission aren't that great of a choice, so I would recommend getting a GL-4 only rated gear oil for manual transmissions, and any GL-5 gear oil for differentials.

Typically the GL-5 synthetic gear oils contain friction modifiers for limited slip, which is apparently the reason for bad experiences in manual transmissions. Redline has some GL-5 gear oils that do not contain the friction modifier for limited slip, and those have some good reviews.

Give us some more information and we can give you some better choices for gear oils.

 

[Ron77]

1978 3/4 ton Ford 4x4. NP 435/205 tranny/t-case, 60 series diff's.

 

[Ron77]

I forgot, the tranny and diff's call for 80-90 gear oil and transfer case actually calls for 50wt motor oil, but my parts guy at the Ford dealer says 80-90 gear oil works just fine.

 

[TimVipond]

Amsoil's application charts go back to 1980. Might be best to call Amsoil tech support at (715) 399-TECH . You may have to call Ford to determine which modern specifications you need. It looks to me like the Amsoil Severe Gear 75W90 will meet your differential needs. And Amsoil's ATF in the transfer case.
For a 1980 FORD TRUCKS F250 HD PICKUP 6.6L 8-cyl Engine Code Z
Manual Transmission,.....EP
80W
Automatic Transmission.....MA5
Synthetic Automatic Transmission Fluid
Differential, Front .....GL-5[1]
80W-90
SAE 80W-90 Synthetic Gear Lube
Severe Gear 75W-90
SAE 75W-90 Synthetic Gear Lube
Standard Differential, Rear .....GL-5
80W-90
SAE 80W-90 Synthetic Gear Lube
Severe Gear 75W-90
SAE 75W-90 Synthetic Gear Lube
Controlled Slip Differential, Rear .....GL-5*[1]
80W-90
SAE 80W-90 Synthetic Gear Lube
Severe Gear 75W-90
Transfer Case,.....MA
Synthetic Automatic Transmission Fluid
Torque-Drive™ Synthetic Automatic Transmission Fluid (ATD)
Fluids
Power Steering Fluid.....FA
Supershift Racing Transmission Fluid
Brake Fluid.....HBH

Automatic Transmission, Initial Fill..........3.0 quarts[2]
Automatic Transmission, Total Fill
3 speed C4..........10.0 quarts
3 speed C5..........11.0 quarts
3 speed 2wd C6..........12.0 quarts
3 speed 4wd C6..........14.0 quarts
Manual Transmission, 4-SPD BW T18-19..........7.0 pints
Manual Transmission, 4-SPD NP435..........6.3 pints
Manual Transmission, 4-SPD NP435 W/E..........7.4 pints
Manual Transmission, 4-SPD Others..........4.4 pints
Manual Transmission, 3-SPD..........3.6 pints
Differential, Dana 44 Front..........3.6 pints[3]
Differential, Dana 50 Front..........3.8 pints[3]
Differential, Dana 60 Front..........5.9 pints[3]
Differential, Dana 60 Rear..........7.0 pints
Differential, Dana 70 HD Rear..........5.9 pints
Differential, with 8.8 or 9 ring gear Rear..........6.3 pints
Differential, Dana 70 EX HD Rear..........6.5 pints[3]
Differential, Dana 80 Rear..........8.4 pints[3]
Differential, Dana 60 Rear..........5.1 pints
Differential, Dana 70 Rear..........7.0 pints
Differential, Dana 70 HD Rear..........5.9 pints
Transfer Case,..........6.3 pints