Hi All,

My 1992 sc400 has always had its differential fluid changed/drained at a Lexus/Toyota dealership.

I am taking it to a private garage this time around and purchased some synthetic 75w90 gear oil. I assume Toyota does not use synthetic.

Is it okay to mix 1.5L of synthetic differential oil with the rest?

Or does a differential drain, drain ALL LIQUID out of the differential?

Thanks!

 

drain all old fluid and put all new fluid in it. synthetic or not. for regular street driving i would bother doing diff fluid change more often then every 60,000 miles. organic fluid or synthetic.

if you track your car or do a lot of hard driving then do it a bit more often. i do mine once a year usually.

if i track it a lot over the summer i change the fluid every other track day. if you have a clutch type lsd you need to change it every other track day as well.

i would say change the fluid and dont bother doing it again. i doubt you do enough with your car to break down the fluid. the diff fluid is not there for lubrication like in the motor. its main purpose is cooling of the gears.

 

I would recommend some of AMSoil's lifetime gear fluid if you are not planning on having alot of drain/fill intervals.

 

Does draining the differential fluid drain ALL of it? Or does it just drain a portion of it (Much like an ATF drain)?