[odysseus]

I've been using synthetic since the first oil change on my 3.2. Mobil 1 5W30 for me, changed when the oil life indicator hits about 20% (normally about 7K miles).

I haven't switched to synthetic in the trans or rear end, but I did have the transmission and differential seals replaced under warranty, which required removal. I presume they drained and refilled them.

I'll need to check the Helm manual, but the manual trans may take ATF, similar to a T5 manual trans, and not manual trans gear lube. Just make sure you get the right stuff!