I use Castrol 10W-40.

It uses the silppery kind. ;)

In my 1997 pickup I use 10W30.

Manual says 5w30 for most temperatures

Striker

i use in my 95 with 147,000 valvoline max life 10w-30 this is what the
nissan dealership recommended.

Great truck so far! Did have the trans rebuilt back at 95,000. That was
2,000.00. Ouch! but i had the whole clutch assmbly replaced, all seals and
5th gear. (it made a loud whine around 50). I also had the real nissan parts
put in the tranny not aftermarket.
Also i have replaced the idle speed control. and another idle device on the
throttle.
Now i also change my oil every 2500 miles. That when it seems to start
getting real dirty.

All in all its a great truck for basic driving needs. The kinda slow, but it
gets a steady 20+ mpg on the highway and 24+ on the hwy.

good luck!