fluid change questions

[98panda]

hey all,
i have a 98 ms 4x2 2.4l, 2wd
im trying to get the most MPGs out of this thing, i was wondering if a good diff oil change and trans flush and run synthetic in both will help? im sure it will, i have seen other vehicles swap to full synthetic add hp and improve gas mileage, HOWEVER....
my major concern is is that this truck has 188+k miles on it, think its too late to go synthetic? im worried about possibly causing leaks.
I know that the trans and diff call for the same weight gear oil, does the 2.4l come with a limited slip diff? its too weak to do the burnout check lol, please let me know guys
thanks
i ask about the diff being LSD because i know i will have to get the 4oz bottle from mitsu dealer additive
thanks again all

[buggzyy]

Mits. sells the LSD oil in a 4L can that will be plenty for your rear a couple times over and you won't need the additive. this is the oil it calls for anyway. Your Rear diff oil requirments are differnent than the trans. the rear call for
SAE 90, 85W-90, 80W-90 GL-5 hypoid gear oil
the trans calls for
Hypoid Gear Oil SAE 75W-90W or 75W-85W
Conforming To API Classification GL-4

The 90w is Mitsu's LSD oil but its used in non LSD diff's on many models.
I wouldn't expect any sudden leaks by switching to Synthetic oil. as for improved fuel milage I really don't know. but the cost for the oil vs the savings is kind of a wash.

[98panda]

well i doubt the fluids have ever been done on the truck thats why i kinda wanted to do it

[LimitedOThree]

panda, i went full syn a few years (front rear difs and engine oil) and saw no gains any place. But it's good to know that what is in there is the best on the market, even though i got nothing out of it mileage wise.