Millers Classic Gear Oil EP 80W90 GL4

80W-90 GL-4 gear oil for classic gearboxes, transaxles and overdrive units

Millers Classic Gear Oil EP 80W90 GL4 is a mineral SAE 80W-90 extreme-pressure gear oil for gearboxes and differentials that need an EP lubricant at GL-4 level.

According to Millers Oils it is also suitable for rear axles that do not need a hypoid oil, and is recommended for gearboxes with overdrive.

Key properties

• Grade: SAE 80W-90, API GL-4, MIL-L-2105, mineral base oil
• Viscosity: 151.6 cSt at 40 °C, 14.5 cSt at 100 °C, viscosity index 93
• Density 0.893 at 15 °C, pour point -30 °C, flash point 220 °C
• Suitable for gearboxes, transaxles and overdrive gearboxes
• Can be used with brass and bronze components
• Packs: 1 L, 5 L, 20 L and 60 L

Choosing the right oil

80W-90 is the most common gear oil grade in older manual gearboxes, and GL-4 is the level many classic synchromesh boxes were designed around. If your manual asks for an 80W-90 or SAE 90 gear oil at GL-4 or at MIL-L-2105 level, this is a typical fit; compare it with the SAE 80 and SAE 90 Kroon-Oil Classic Gear products if the handbook names a monograde.

A pour point of -30 °C makes this the better all-season choice among the shop's GL-4 gear oils. Check, however, that the rear axle does not need a hypoid GL-5 oil, as some differentials do; in that case use one of the Differential Oil products instead.

The 20 L and 60 L sizes are practical for garages and clubs.