I just started using wax emulsion and think it's making a big difference in the amount of end checking I'm getting. I had some Advantage Lumber end sealer left over from my deck project this Summer so I decided to use it on the WO logs I just milled. I've always used whatever left over paint I've had lying around up until now and it did a pretty good job, but I think the wax emulsion is better. I haven't seen a single check that wasn't already in the log ends when I got them. I think I'm a convert. Plus it's clear so I can see the grain underneath.
John