Personally, I have installed countless Jasper engines and transmissions. I am an ASE Certified Master technician and I seem to be installing quite a few units each year. My experience is that I've never had an engine or transmission in any vehicle I've placed one in, fail. Now, as far as oil leaks, I can count on one hand, units I've replaced because of leaks. I don't know the reason for the leaks, but Jasper was very prompt for replacing the units and paid all labor associated with changing the units out. I, as a tech also was paid full time instead of warranty time, meaning that Jasper wasn't skimping on paying out the labor claims either.
I did have the opportunity to visit their remanufacturing facilities in Indiana. They paid to fly a group of us there, cover all our expenses to visit. They process quite a large amount of units each and every day and their processes seem to be top notch. Everyone from the head of the company to the builders wore white shirts, traditional and classy, just trying to keep everyone feeling like they're on the same level. Talking to the workers there, they were taken care of well and the amount of work it takes to reman these units is phenomenal!
I do know, that when Jasper remans a unit, they will make all the updates to an engine or trans that would have been necessary to correct any known manufacturing problems, which being the case, their units come out of the factory better than when it was built new because the problems have already been addressed.
Anyways, just my 2 cents....