A Guide To Wheel Bearing Grease
Wheel bearings turn at high speed. A good quality wheel bearing (like GMB wheel bearings) has a very refined design. The design allows for minimal friction and maximum longevity. Yet, wheel bearing grease is always necessary.
Grease should be packed into the wheel bearing and the following areas:
- The housing
- The wheel end’s inside surfaces (where the bearing sits)
- The cavity surrounding the bearing
Wheel bearing grease provides lubrication and prevents corrosion. Without wheel bearing grease, the bearing and the areas around it can rust. That will affect the bearing’s performance.
This comprehensive guide on wheel bearing grease has all the information you need.
What Is Wheel Bearing Grease?
Let’s start with what wheel bearing grease actually is. It’s not just oil. It’s a combination of different ingredients:
- Oil such as:
- Mineral oil, vegetable oil, or synthetic oil
- This thickens the oil enough to give it a grease-like consistency
- The soap is non-detergent soap, but rather made from fatty acids with anti-corrosive properties
- Additives such as:
- Anti-corrosion additives
- Water-resistant additives
- Anti-wear additives
Each wheel bearing type and brand has its own blend of ingredients.
Synthetic vs Conventional Wheel Bearing Grease: Which Type Should You Get?
In the old days, only one type of oil was being used in wheel bearing grease. It was petroleum-based oil, commonly known as mineral oil. Now, we’re seeing synthetic oil in more and more wheel bearing grease formulas. It’s no surprise, because:
- Synthetic oil is less expensive than mineral oil
- Costs of synthetic grease ingredients haven’t risen as fast as mineral oil base ingredients
- Synthetic oil offers more benefits than mineral oil
- Better heat resistance
- Longer life
- Less friction
If you ask us, synthetic oil based grease is the way to go.
The Different Types Of Wheel Bearing Grease
There are different types of bearing grease. Let’s talk about the most common ones:
1. General Multi-Purpose Grease
General multi-purpose grease is made with calcium sulfonate. You can use it on a variety of applications including:
- Drum brake wheel bearings
- Chassis components
This type of grease is resistant to water. Yet, it doesn’t perform well under high temperatures. That’s why you should never use this grease on high temperature applications. For example, disc brake wheel bearings.
2. High Temperature Multi-Purpose Grease
This silicone-based multi-purpose grease is suitable for high temperature applications. The presence of silicone helps this grease stay stable under high temperatures. It also protects the grease from other elements commonly exposed to wheel bearings. This type of grease also performs well in applications that don’t generate high temperatures. It’s more versatile than general multi-purpose grease.
Moly-grease is a type of grease that contains molybdenum, an anti-wear additive. Wheel bearings by some automakers (like Ford) require moly-grease. It’s because the grease provides higher-pressure protection for the metal. Check the owner’s manual to find out which type of wheel bearing grease the automaker recommends for the vehicle
4. Marine Grease
Marine grease is ideal for boats, boat trailers, and other vehicles that are dunked in water. Marine grease is loaded with water resistance additives. Bearing grease in general comes with soap, but soap can be water soluble. So you want to make a point to use marine grease if you know your bearings will see a lot of water.
How Is Wheel Bearing Grease Rated?
Each wheel bearing grease formula has a rating. The rating tells you a lot about the type of wheel bearing grease it is and what it’s good for. The grease is rated based on how soft or firm it is. Softer greases are easier to pump with a grease gun, while very stiff greases can’t easily be pumped.
What The Letters Mean
The best letter rating for wheel bearing grease is GC-LB. Here’s what the letters mean:
- G means that it’s certified for use in automotive wheel bearings
- A means good
- B means better
- C means best
- L means that it’s certified for use in automotive chassis
- A means good
- B means best
When shopping for wheel bearing grease, look for the GC rating. You could go with GA or GB, but GC is always the best one. If you’re looking for grease for the chassis, look for the LA or LB rating.
What The Numbers Mean
Each bearing grease type comes with a numerical rating that indicates its thickness. Bearing grease comes in a wide variety of thicknesses. The numerical rating helps you pick the best one for your application.
Most commonly, the numerical rating ranges between 0 and 6. The 0 rating indicates that the grease is soft, in an almost liquid-like consistency. The 6 rating indicates that the grease is quite hard, with a consistency that’s like a firm cheese. Most wheel bearing formulas come with a rating of 2. This indicates that the consistency is similar to peanut butter.
Why You Should Not Mix Together Different Types Of Wheel Bearing Grease
You can mix together some oils used in bearing grease. For example, plant-based oil and petroleum-based oil can mix freely with each other. If you want to know if the new bearing grease will mix well with the old bearing grease, you can do some research.
If you ask us, though, it’s always better to play it safe. If you mix together two incompatible types of grease, your wheel bearings can fail. It’s because not all soaps are compatible with each other. Mixing together two different types of soap can result in the soap separating from the oil. This will render the grease useless.
The best way to ensure that the old grease doesn’t mix with the new grease is to replace the grease. That means thoroughly removing the old grease before packing the new grease into the wheel bearings. Here are some liquids you can use to clean out the old grease:
- Paint thinner
- Hot soapy water
- Brake cleaner
In some situations, it can be hard to remove the old grease. If you can’t do it, that’s OK. Just make sure the grease you used before is the same as the one you will be using. You can try to pump out the old grease with the new grease using a grease gun. The new grease will push out the old grease.
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