Picture
shows how boot was designed to be installed. A lot of
people mount them upside down; which may increase the
stress on the boot. These boots, still made by Nissan's
manufacturer in Japan are not out of the most oil
resistant material available and can deteriorate rather
rapidly at times. To combat this I've seen a lot of
interesting attempts at protecting the boot. Sheets of
flat rubber and plastic funnels attached to transmission
tunnel underneath boot seem to do a good job although it
looks a bit weird. I've even had people tell me they've
had good luck spraying the bottom of the boot with
silicone spray now and then. It would be nice if you
could just deal with some of your oil leaks, but that's
not always feasible.
The
other factor that tears up boots is worn or loose shifter
parts both in and out of the transmission. These can all
multiply each other's effects and combine to make a lot
more stick shift movement. You may notice a remarkable
difference in your shifter by replacing the pins on the
outside of the transmission if they are loose; and
cutting some thin shim stock to take the side to side
wear out of the picture that develops in the cast iron
bracket that straddles the rod that goes into the
transmission. The rubber grommets immediately below your
chrome lever are designed to be clamped by two large
washers that fully compress the rubber. Without that
clamping force the shifter will also tend to feel sloppy
and imprecise.
You
can if you choose; use the two part 67 1/2 boot. It uses
an almost flat rubber seal, with a "dress-up" vinyl boot
above.