Redline 75W140 GL-5 Gear Oil Gallon

Redline 75W140 GL-5 Gear Oil (Gallon)

This Redline 75W140 gear oil is a fully synthetic differential oil built from polyol ester base stocks. As a result, it holds up under the kind of heat and load that breaks down conventional gear oil. It also meets API GL-5, GL-6, and MT-1 specifications, along with MIL-L-2105E and SAE J2360. Because of that broad spec coverage, it suits both hypoid and non-hypoid gear sets across a wide range of differential designs. It already includes friction modifiers suited to clutch-type limited-slip differentials, so most LSDs won’t need any extra additive on top.

Because the ester base stock is so slippery, we don’t recommend this Redline 75W140 gear oil for manual transmissions or transaxles. That same slipperiness can cause synchro mesh issues and rough shifting, so Red Line built it specifically for differentials instead.

Built for Heavy-Duty Differential Service

Compared with conventional and other synthetic gear oils, Redline’s shear stability holds up for longer and resists oxidation better. As a result, you get better differential efficiency, longer drain intervals, and less wear on the gears themselves over time. That added stability matters most in differentials that see sustained high loads, such as towing, off-roading, or track use, where oil temperatures climb well above what a standard differential sees on the street. This gallon size suits workshops doing multiple fills, or anyone topping up a larger diff or transfer case that calls for a 75W140 GL-5 gear oil.

Typical Properties:

• API Service Class: GL-5+
• SAE Viscosity Grade: 75W140
• Viscosity @ 100°C: 27 cSt
• Viscosity @ 40°C: 192 cSt
• Viscosity Index: 191
• Pour Point: -45°C / -49°F
• Brookfield Viscosity: 1300 poise @ -40°C

Not sure how much oil your differential holds, or whether 75W140 is the right viscosity for your setup? Get in touch and we’ll help you get it right the first time. A Quart size is also available if you only need a smaller top-up. For the full technical data sheet, see Redline’s official product page.