synthetic gear lube

jw,

I have never used synthetic oil in a tractor, but I have tried full synthetic 15w in my plymouth roadrunner. I did not have any problems with it leaking past the main seals, however the engine did burn off a significant amount of oil compared to regular 15w oil. For whatever reason the synthetic oil slipped past the piston rings in much greater quantity compared to regular 15w. I have read that since synthetic oils are artificially created and the oil molecules are all uniformly smaller, synthetic oil slips past the larger bearing and ring tolerances in older engines. I have also read that synthetics have a large amount of cleaning detergents that can swell gaskets and seals in older engines that are not designed for synthetics. I would stick with regular gear oil, certainly cheaper. Just from my experience, hope this helps you.

Synthetic oils never have had a problems with seal in any application.  What was the problem, when they first came out, there was some very bad oils out there that left many deposits.  These deposits would form false seals that would close off the oil to the original seal causing it to be destroyed, but the false seal would keep it from/slow the leak down.  When you put synthetic oil in, it cleaned the deposits and broke down the false seal.  Then those not knowing any better blamed the synthetics for causing the leak. 

Modern dino oils are where synthetics were 15years ago do the the increasingly stringent specifications.  So you don't see the false seals happening with vehicles now. 

I use motor oil for less weight on the puller.