Oil Bath Boat Trailer Hubs… should I convert?

Oil Bath Boat Trailer Hubs… should I convert?

Date: September 2, 2013



Oil bath hubs have received quite a bit of buzz in the boat trailer industry. Many trailer manufactures and end users alike have made the switch over to oil filled hubs as opposed to traditional grease. Ever wonder why? Are oil filled hubs really that much better than grease? With all this talk about oil bath hubs hubs, you would think that they turn your trailer into a space shuttle and automatically launch your boat for you! .. Okay, we know that’s not going to happen, but what gives? Why are they so great.. or not so great?
More after the jump…..
I am always getting phone calls from customers telling me that they want to switch their grease bearing buddies over to an oil bath hub system. Curious as to why, I always respond and ask …. why? Typically I always get these answers in return (not in any particular order)

1. Because I have heard its much better than grease.
2. It seems like it would be easier to maintain.
3. Just seems like it would be better than grease.

Hm mm.. Okay, well let’s look at the advantages and disadvantages of both.

Oil Bath Hubs have been used in the trucking industry for years. They seemingly work well and with little maintenance. So .. they must work great on a boat trailer too? .. ugh.. we’ll lets see. First off lets keep in mind that tractor trailers are on the road constantly. They rack up thousands of miles that are continually being put on the hubs keeping the bearings very well lubricated.

Boat trailers are a completely different animal. Boat trailers sit 99% of the year (think about it, that’s probably you!) Okay, sorry… there are those folks who go boating so much that there trailer only sits 95% of the year (sorry if I missed you)… Now, that we cleared that up, lets talk about you and your trailer!

Point #1
Boat Trailers function in a completely different fashion than a tractor trailer big rig. The fact that boat trailers sits so much means that if you have oil bath hubs, all the oil inside the hub sits as well…. Think about it…. All the oil is collecting at the bottom of the hub only lubricating one-half (if that) of your bearings…. When your boat trailer sits like this (in storage , especially in winter) the condensation also becomes an issue. With many oil bath hubs, it is necessary to rotate the wheels every other week or so to prevent rusting and pitting of the bearing surfaces. (Hey honey, I’ll be back in a couple hours, gonna rotate the wheels on the boat trailer)… yeah that’s gonna happen!

Point #2
Boat trailer hubs will heat up during long trips and when your arrive at the launch ramp they are dipped into much cooler water, the sudden temperature change could create a vacuum affect inside the hubs. This “vacuum” affect could draw condensation, moisture, and impurities directly into the bearings. (not good)….
(But wait, I have been using oil filled hubs for years and that has never happened to me….. My answer: that’s great!)

Point #3
Tractor trailer drivers are professional, they drive for a living. On the other hand, you’re not! (but wait, I have a class x, y, z license I know how to drive) again, that’s great! ….. back to the point. If you are towing and you knock an oil cap off, you are done. By done I mean on the side of the road with a blown out hub, axle, wheel, etc…. Hit a curb the wrong way, take a turn to short, or just have a cap fall off and your going to lose every last drop of oil inside the hub. No lubrication = Not good = Expensive Tow Bill. Remember also to consider that if this happens, you’ll have to replace at minimum the wheel hub/bearings & seal which means additional $$…. Not to mention possibly having to replace the axle (damaged spindle), brake calipers, rotors, blown tire, fender damage from the blown tire, etc, etc, etc.. you get the idea..

Now, If you were to do this with a grease cap your not going to lose all your grease. Sure, grease is going to spit out everywhere and make a mess! But you’ll most likely be able to complete your trip and get back home before you even knew you were missing a cap and it probably will only cost you $20 for a new cap and some new grease.

Final Thoughts:
Oil bath hubs should be checked after every loading/unloading cycle to make sure water has not penetrated and diluted the oil. Small leaks can cause the oil to escape, once this happens bearing failure is imminent within a few miles. Most oil bath hubs are only half filled with oil and constantly inspected to maintain the proper level. Too much or too little oil could cause problems.
By comparison, standard grease bearing protectors make it easy to visually check the amount of grease inside the hubs. The internal spring piston exerts about 3 p.s.i. against the grease to ensure that no water enters the hub when the hub is submerged during loading and unloading. When properly maintained there are no voids inside the hub where condensation can form during storage.

Okay, didn’t want to take the wind completely out of everyone’s sails, but the simple facts are the facts. Ohhh and PLEASE don’t tell me that you have been using oil bath hubs for years on your boat trailer and you never have had an issue… and prior to that your had grease and had 500 issues… Remember that 20 different people will tell you 20 different stories about their experiences. I am just telling you mine. Just remember this post when your on the right shoulder of your local freeway waiting for a tow!