Does a 4.77 final drive diff need other oil than the OEM 4.1 ?

I know popular oils are:
75w90
75w110
75w140

thanks

 

75w 140 is fine.

 

Better than the thinner stuff?

 

"old 90" grade (the SAE spec changed maybe 20 years ago long after the last S2000 was built) corresponds to the "new 110" grade. 75W-110 in my differential the past few years. 75W-140 is not burning up differentials according to posts here. Remember multigrade lubricants have several personalities and act accordingly.

-- Chuck

 

So basically the fact if it concerns a 4.77 ring and pinion or stock 4.1 doesnt make a difference for the oil of choice?

 

I'd error on the thicker side, 75w140. I ran that in my stock diff at the track and when I drained it there was always very little material on the magnent. The thicker oil isn't going to do any harm to your gears, now that I have an OSG I run 80w250.

 

For our diff, thicker is actually better.
Go for a 75W-140 synthetic.

 

What I havent gotten clear yet is if these reccomendations are for our diff in general or specific if you use 4.77 final drive? I dont do track. My MY00 has very bad mpg and here in Holland the fuel is extremely expensive nowadays. (More than 2 USdollars per liter sometimes 2,50 to 3). Does w140 have a bad influence on Mpg vs 90 or 110 or doesnt it make any difference? That would be my only concern. Any idea about this?

 

Prolly 4.77 ratio has a much more adverse effect than 75W-140 differential oil.

 

Its not installed yet so I dont know. I drive a lot around town and less highway so I have to see. For stop and go it should have a beneficial effect if there is any. How the extra rpm affect highway will find out. Like I said. My mpg is very low. Even if I drive in low rpm. I vtec when I can. Low Rpms around town (driving high gear) dont seem to make much difference.

I average about 15-18 Mpg.
on highway trips its about 21-24mpg

Is this nornal at all? (Stock diff stock engine 215/245 tires)