jacknbella wrote:
Are you sure that it is a grease zerk or a breather valve of some type instead? Both look similar, at least mine do.... Do you also have turbo lube hubs? Just curious
Honestly I am not 100% sure of anything because this is the first time I tried this. I didn't worry about this too much in past because I haven't used it much except once a season to take the boat to the marina and bring it back at the end. I also have a triton trailer with sure lube and the setup looks the same on my four winns. It has a rubber cap similar to this:

When you remove rubber cap, you see something like this:

On the other 3 wheels, it worked like this:

The last wheel, clear grease started coming out right away, but then I noticed that it was being pushed out of the sides of the fitting on the grease gun. On other 3, I definitely saw different color grease coming out for many pumps until it turned blue, the color of the grease I was using.
Also, my trailer looks identical to the trailer in the picture in your signature except for that it's red.