I've had the same jack stand on my sled since '93. I did pop the top off and add grease last year.

When I store the boat, I use the jack to lift it, then use auto jackstands under the frame members. This keeps the front of the boat higher than the stern for drainage and takes all the weight off the jack. Since I have to lift the tongue higher than the jack will extend normally, I do it in stages with a couple of 4X8 blocks to go under the jack.

Remember to chaulk the tires before you start. Makes the boat a lot harder to steal since, even at full extension, the jack will not reach the ground without the blocks.