Gear oils for drive axles, differentials and manual gearboxes

In a drive axle the ring and pinion slide against each other under the torque that drives the truck, so the oil has to hold a film between the teeth, carry heat away from the bearings and keep the housing free of rust. The lineup covers four SAE grades: 75W-90 and 80W-140 as full synthetic gear oils, and 80W-90 and 85W-140.

Bedrock dealers sell these oils by the 5-gallon pail to fleet shops, owner-operators, repair shops and construction, farm and oilfield operators along the Gulf Coast. The first number in each grade describes cold flow and the second describes the oil's body at operating temperature, so the right pick depends on the axle maker's chart, the load the truck carries and the weather it works in. Product Data Sheets and Safety Data Sheets for every grade are available on request.

How to choose

• On-highway drive axles whose maker lists a 75W-90 full synthetic: Bedrock 75W-90 Full Synthetic Gear Oil
• Axles, differentials and manual gearboxes whose chart lists 80W-90 in mild and warm weather: Bedrock 80W-90 Gear Oil
• Heavy loads, low speeds and summer heat, where the chart lists a 140 grade and the fleet wants a full synthetic: Bedrock 80W-140 Full Synthetic Gear Oil
• Axles and gear cases whose maker lists an 85W-140 for warm-weather, heavy-load service: Bedrock 85W-140 Gear Oil
• Switching an axle from 80W-90 to a full synthetic: drain and refill rather than top off, and note the change in the service record (Bedrock 75W-90)