what oil do you use in your vx only!

[mkiVX]

well after searching and searching it seems like every one has a different opinion


i have a 92 vx that i acquired at 150,000 and have been running 5w30 mobile1

i was wondering what is the lowest viscosity that i can run safely
please chime in if you own a vx or know about vx.
i live in the mountains/high desert are of california
to be exact Oak hills/ hesperia area
it gets pretty hot in th summer and below freezing in the winter

looking for better FE and how many more mpg do you think i will get with lower viscosity
thanks guys!