By Tony K
Sorry this is not an endorsement for synthetic as I didn’t have any luck when I put it in my gearbox. And by no means do I blame the particular brand of oil I used. All the fault lies with the worn out parts inside my gearbox.
I was having some problems with 3rd gear in my H55. Diagnosis looks like the 3rd gear synchro ring is worn out. At this point I am not quite ready to pull the tranny apart (but that is coming). Then I noticed on the forums that synthetic gear oil seemed to be popular so I gave it a try. Wrong thing to do in my tranny, went from poor downshifts in 3rd to no down or up in 3rd without grinding. Had to go back to regular gear oil, 80-90wt if your curious as to what I use.
But some of the claims for synthetic are true. The noise from the gearbox was definately quieter and shifting in all other gears actually got smoother. In a perfectly functioning tranny would I try it again, yes. In an old less than perfect one, no.
-Time for an Update-
Finally got that synchro fixed. And just for the heck of it I put the synthetic oil I removed back into the tranny. All in all it works just fine with one concern. Frequently the seals and synthetic do not get along and I think this is a minor issue with my tranny. I think the main problem is the 5th gear shift rod seal, yes it leaves the top of the gear box in two places. I have new seals for it but it requires that I take the gear box and t-case apart again. And this is not likely to happen anytime soon.
