Rick's Free Auto Repair Advice

Wheel bearing grease versus chassis grease

Wheel bearing grease versus chassis grease

What is grease?

Think of grease like a sponge filled with oil. The “sponge” portion is actually non-detergent soap made from fatty acids with anti-corrosive properties, water-resistant additives, and anti-wear additives. When combined, this combination turns into a kind of gel. Oil is added to the gel to form the grease.

What is wheel bearing grease?

Wheel bearing grease is designed to handle the high shear levels that occur between the ball or roller bearing and the race. It’s also designed to run at high heat, so it can handle high running and braking temperatures.

Many high-temperature wheel-bearing greases are made with a silicone base to maintain stability at high temperatures. The more expensive wheel-bearing greases also contain molybdenum an anti-wear additive. Some carmakers required molybdenum wheel bearing grease.

Wheel bearing grease ratings

The rating is a four-letter combination as shown below.

wheel bearing grease rating

Wheel bearing grease thickness rating

Wheel bearing grease thickness is rated on a 0 to 6 scale, with 0 denoting a soft, almost liquid consistency and 6 denoting a “hard” or “thick” consistency equivalent to soft cheese. Most wheel bearing greases for automotive use are rated at 2, a thickness close to creamy peanut butter
Wheel bearing grease versus chassis grease or general-purpose grease

Grease can be rated for wheel bearing use as well as chassis use to lubricate ball joints and tie rod ends. However, to use a chassis grease for wheel bearings, it must contain the “G” designation or it isn’t rated for the higher temperatures found in wheel bearings.

Can you mix different types of greases?

No. When repacking wheel bearings you should not use different types of grease. In fact, you should thoroughly remove all the old grease and repack it with fresh grease. Old grease has worn out anti-corrosive and anti-wear additives, along with components of thermal breakdown. Combining new grease with old grease will result is less optimal lubrication and cooling.

This applies to chassis grease as well. If the ball joint or tie rod end isn’t sealed, pump in the new grease to force all the old depleted grease out.

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Posted on by Rick Muscoplat

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