Maintenance of wheel bearings is often overlooked. Unfortunately, this neglect can cost you hundreds of dollars in damage and leave you stranded on the side of the road. Whether for your RV, camper, or boat trailer, the method of greasing your wheel bearing is very similar.
The great news is that with a few dollars and a little time, you can put fresh grease yourself and avoid the pitfalls of damaged wheel bearings.
Often, people try to give a general rule of thumb as to how often to grease your wheel bearings. You may have heard about greasing your bearings every 10,000 miles as the hard-fast rule. Although this can be a good rule of thumb, there are certain factors you want to consider before trusting this very general number.
In this post, you will learn the factors that will affect how often you should consider applying grease to your trailer bearings.
Table of Contents
Types of Grease
The first step in knowing how often to grease your trailer bearings is to first understand the type of grease being used and its longevity. Say I asked you how long motor oil lasts? Well, as you know, there is convention oil and synthetic oil. Some synthetic oils claim to last 15,000 miles, while others don’t make any claim and fall under the 3,000 miles that our dad thought us.
Bearing Grease is no different since it is a petroleum product. Some bearing grease may be engineered for longer-lasting and for higher temperatures than others. Check your manual on the recommended grease for your travel trailer wheel bearings. My axle manufacturer-recommended grease that complies with NLGI2 grease.
For your boat trailer, you will want to look into marine wheel bearing grease. This kind of grease is hydrophobic so it repels water more effectively. Not a bad idea since your boat trailer goes underwater. More on that below.
EZ Lube Axles
If you have EZ Lube Axles, you might think this is the best next thing to sliced bread! Well, I have friends who have learned the hard way, that EZ LUBE Axles with a grease zerk can cause more damage than good. Let me explain.
For a boat trailer, that will be submerged in water, the EZ Lube Axles are great. By pumping new grease with a grease gun into your zerk fitting, you’re pushing out old grease and replacing it with new grease. This fills the entire axle spindle with grease. Great for keeping out water for your boat trailer going underwater.
Problem is that you are relying completely on the grease seal to hold in the grease and not go all over your brakes. And since you are just pumping with a grease gun, you have no idea that the grease is going past your back seal onto your brakes. This happened to my father-in-law and he had to replace the axle. No fun.
For travel trailer wheel bearings, since you will likely not submerge your axle completely underwater like a boat trailer, I would stay away from using the zerk fitting and go by the tried and true way of removing the wheel and hub to repack your bearings.
I personally called Lippert and asked what they recommend. Even though they still provide the EZ Lube Axles, they recommend not filling the axle void space. They prefer simply removing the wheel and manually packing the front and rear bearing. And then if any grease on your wheel hub, you can easily clean it with brake cleaner before reassembly.
Factors
10,000 miles for greasing your bearings is a good rule of thumb. However, considering any of the factors below should increase how often you replace your bearing grease.
Speed
One of the main factors to determine how often to replace your grease trailer bearing is speed. If you travel mostly at high speeds on the freeway, those RPMs on your wheels are putting extra strain on grease protection. Lower speeds and off-highway speeds will help the longevity of your bearing grease.
Heat
Just like with motor oil, grease loses some viscosity (and protection) when driving in high heat situations. Many Lithium-based bearing greases are rated at 500 ° F. You may be thinking, well, it never gets that hot outside, so I will be good. Well, if you have old grease and added friction, guess what, your bearing and axle are getting very hot. And add in a 90 ° day, you can get to 500° pretty quickly.
Missing Components
Last month, my buddy sent me a text about his bearing cap that was missing and he was looking to find a new one. Looking at his photo, you can see that dirt and grime got into his bearing. Sure enough, when we changed his grease bearing, it was dry, dirty, and ready to cause some major damage. I also bet some water got in there when he was driving in the rain. Had my friend just waited for 10,000 miles, this wheel bearing would have been destroyed and he may have needed a new bearing or even an axle.
Mis-installation
Your bearing needs to be not too tight and not too loose. If you had your bearings greased by someone else, and they tighten the castle nut too tight, that is causing additional friction and heat to your bearing. The bearings are being pressed and not allowed to move freely as intended.
Also, on the other side of the coin, too loose causes a lot of unnecessary movement to the bearing surface and can cause heat and premature damage. This will also cause your wheel to move back and forth down the road causing premature wear to your bearing and axle.
Non-compatible grease
Using the wrong grease or non-compatible grease will shorten the life of your grease and can quickly cause premature wear. The best way to check this is to refer to your axle manual to see the grease recommendations. Make sure to use the recommended grease all the time when replacing old grease with new grease. My RV wheel bearings call out for Lithium-based grease meeting NLGI2 specs. You can double-check that spec on any bearing grease label.
Time
Time is also a major factor in how often you should change out your old grease. As time goes on, moisture and contaminants will break down the old grease and reduce its ability to protect. By using the rule of thumb of 10,000 miles, it may take you years to get to that mileage on your trailer. When considering time, after a few years, your trailer bearing grease could be broken down and not provide much protection.
That is why I recommend replacing your bearing grease once every one to two years, regardless of mileage. Having your travel trailer sit through seasons and being exposed to temperature changes can cause just as much wear and tear to your grease as traveling down the highway.
Final Thoughts
The rule of thumb of 10,000 miles to grease your trailer bearings may sound like an easy and guaranteed way to keep your bearings lasting a long time. However, as you learned, this rule of thumb number can be misleading, and often times service to your bearing is needed sooner.
Another great tip shared was that EX Lube Axles can be great and pumping your axle void with grease should be limited to only boat trailers and is not recomended for trailer or RV bearings. The best method is to remove the wheel and manually regrease your inner bearing and outer bearing. This will allow less potential damage to your bearing seals and have grease all over your brakes.
And as always, anytime you remove and replace your wheel, Torque your lug nuts to the manufacturer’s recommendation by using a torque wrench. And to re-torque the lug nuts after so many miles of travel (check your tire sticker on your RV).
Safe travels!
For more great info on Zerk Fittings, visit How Often To Grease Zerk Fittings.
Tony is an avid camper and RV traveler. He fell in love with camping on his first RV trip with his wife over 25 years ago. Tony loves sharing lessons learned and tips about RV maintenance and safe traveling.
