I think it's more like, "When it gets bad enough, I'll go through the hassle of changing the seal." Mine leaks pretty bad based on the oil spots under the tractor, but every time I check the oil level in the axle, it's fine. I think I had to add oil twice in 3-4 years. That's not bad enough to take anything apart, IMHO.
I would say if you cant feel wheel movement when you jack the front end up, should be fine as long as water dont leak in,
