2016 4Runner SR5
Senior Member
Finally got around to changing differential oil, T-case oil, and greased the driveline yesterday. Used Mobil 1 75W-90 in the diffs, and Toyota LF 75W in the T-case.
Everything went smoothly aside from bashing the back of my hand while breaking loose the rear diff fill plug, and accidentally putting the T-case fill washer on the front diff fill plug... caught that mistake after filling the T-case and luckily the aluminum washer wasn’t the least bit deformed after using it on the wrong plug.
Measured the leftover Mobil 1 and Toyota LF oil once I was done, and both were within one ounce of factory fill specs.
Contrary to what some others have found, I was quite surprised about how clean my oil looked, especially given almost 90K miles on it. There was a bit of metal paste on the drain plug magnets, but the clarity of the oil was quite good. The T-case oil essentially looked like the new oil I put in. Diff oil was definitely a different color, but that may be because Mobil 1 75W90 is very light in color. Of course, the condition is simply a guess without a proper UOA!
It seems pretty much everyone finds the transfer case oil is super clean when drained, even with high miles. Unless you have AWD or run in 4WD regularly, your front diff will also be very clear. On a part time 4wd vehicle pretty much all the load is on the rear diff so that oil is going to wear the fastest.