Ed I’ve heard the same rumor many times about synthetic oils causing leaks and ruining
seals but according to the oil companies who have done extensive research in that area
it’s unfounded. That it would cause problems like that doesn’t make sense to me either
since the synthetics base are the same old mineral oils that we’ve been using all along.
And the rubber and application geometry of the seals and sealing surface is the same no
matter what the application. Many if not most of the new vehicles on the road today are
using synthetics throughout and don’t seem to have recurring problems with leaks.

Well Ken I was counting on your experience with your fleet and your past history in the
oil business when I picked the Delvac in September. The synthetic oil still might not be
the problem with the syncros but it's the only factor that really changed and it does seem
to be a logical approach.
I’ve read several reports of syncro slippage problems with Triumph overdrive
transmissions after switching to synthetic oils and the problems go away after switching
back.

The only way to really tell is like I said, I'll drain her out this winter and refill for next
spring with the JT-7. Should know right away. And like I said the cone didn't show any
wear at all and the machine tooling marks in the original syncro ring were still crisp and
well defined, very little wear.
Another possibility is that the difference in the viscosity of the 50w synthetic vs the 85w-
140 multi-grade. The heavier oil might pick up the syncro faster than the lighter oil. That
along with the difference in lubricity could be what's causing the lag.

We'll know next spring. Winter is time for those basement projects that I put off when the
weather is nice above ground.

Denny Graham
Sandwich, IL

Denny G
Sandwich, IL