What Oil For Trailer Bearings?

[Craiger12]

I need to change the oil in my trailer wheel bearings as it has become a little cloudy, indicating the presence of water. It tells me to use 50W oil on the cap, however I'm not sure which type to use. Do I need a specific type of oil, or will any 50W oil suffice?

[Long Mike]

I've never heard of trailer bearings that use oil. Unless you have some sort of exotic "Ferrari" type of trailer, you need to pack the bearings with a marine grade grease. Do a search on these forums for trailer bearings and you will find a wealth of information. Good luck!

[Glenn]

Um...Mike, my bearings use oil too. Most newer 'glass boats have 'em.

And yes, it's 50 wt. Any kind will do. Best thing to do is jack the trailer up and put it on stands. Open up the caps and spin them around so they're pointing down so they'll drain. Then come back the next day to fill them up approx half way. It takes a LONG time to get the oil in that tiny hole, so be sure to give yourself plenty of time to do this project.

[Mudwalker]

Um...Mike, my bearings use oil too. Most newer 'glass boats have 'em.

And yes, it's 50 wt. Any kind will do. Best thing to do is jack the trailer up and put it on stands. Open up the caps and spin them around so they're pointing down so they'll drain. Then come back the next day to fill them up approx half way. It takes a LONG time to get the oil in that tiny hole, so be sure to give yourself plenty of time to do this project.

I used a small oiler can (thumb pump) and it sped the process up some. I also read a post somewhere to use a high temperature gasket sealant on the threads of the plugs to keep them from leaking or coming loose. Been a year and no leaks or problems so I guess it was right.

[Craiger12]

Thanks for the help guys.

Glenn - about how long is long? Are we talking like a few hours?

[Craiger12]

Also, is there some type of adaptor that can be used to help get the oil in the tiny hole or is this going to make a mess?

[Long Mike]

Oil? Well kick me in the groin and call me Shirley. Even at my advanced old age I learn something every day. Thanks for the education guys.

[senile1]

Oil? Well kick me in the groin and call me Shirley. Even at my advanced old age I learn something every day. Thanks for the education guys.

It's the same for me, Shirley. My boat and trailer are from the year 2000. I never realized they were using 50 weight oil to lubricate the bearings in some of the new trailers. It actually sounds like a much cleaner way to keep them lubricated than having to pack them at regular intervals.

[NBR]

Heavy duty (Class 7 and 8)trucks have used oil for years. ( They called them oil bath hubs. Now there seems to be a switch in the trucks to a system called semi grease. I have no clue to which is better.

[South FLA]

Some "oil bath" bearings are COMPLETELY FULL others are HALF or MORE FULL, so make sure you consult with your boat manufacture, trailer manufacture, or bearing manufacturer. I have a Ranger that uses the Cool Hub system with a viewing window, my particular bearing requires that the ENTIRE bearing be filled up. I used high temperature thread compound to make sure the plugs don't leak, read the instructions on that too it has a cure time. Here is a video of how to service Ranger Boat's Cool Hub System.

[Glenn]

Most 50w oil comes in a container with a tapered nozzle like a tube of caulk. Just cut the tip off for a small hole.

Tips:

Do it in warm weather. The hubs will drain much faster. It will take all day if it's below 50 degrees out.

Put the container of oil in the microwave for a few seconds to warm it up. It will fill up much faster that way - trust me!

Fill the hub, let it sit 10 15 mins, then do it again. Repeat until it's at the desired level after sitting for 10-15 mins. Just don't fill it up completely full. I know the hubs pop out and expand when the hubs really heat up, but that's still not enough expansion for a totally full hub. The pop-out mechanism is really just for extreme conditions, and not something you should see happen on every trip. If your hub is too full, you risk popping the back seals.

And yes, dip the threads in high-heat sealant before reinstalling. Otherwise it will leak everywhere.

[bilgerat]

Heavy duty (Class 7 and 8)trucks have used oil for years. ( They called them oil bath hubs. Now there seems to be a switch in the trucks to a system called semi grease. I have no clue to which is better.

This brings up an important point. You need to regularly inspect the backside of your wheels for blown wheel seals. Grease won't leak as bad as oil when a seal fails. Oil will soak brake linings in addition to the danger of wheel loss due to the loss of oil.

Drain tip: A hair dryer on 'high' heat setting aimed at the hub helps speed up drain time. Even better is a heat gun, such as the ones used to shrink wraps. More people have access to a hair dryer though.