1st gen gear oil

I know there is a lot of stuff already typed up on this subject (i've read most) but I still have questions. I've recently started doing some upgrades to my truck (i'll post pics soon) and i'm going through everything. I've read a lot over the past few weeks. And scoured the internet forums and sites. My question is about gear oil. My Tacoma is a 2000 4x4. Book says SAE 75w90 Hypoid oil. I went with Mobil 1 Synthetic 75w90 because it got great reviews and a lot of people are on the synthetic band wagon. Wasn't cheap but couldn't afford Redline either. When I went to change out the rear diff the oil was green (actually looked like green antifreeze). I thought, hmmmm, ok. Well changed front, rear, and transfer case out. Transfer case oil wasn't green though. Went to drive it and started hearing a hum coming from rear end. Only drove about 4 miles so not too worried. But from what i'm learning, 1st gens apparently don't like synthetic oils. At least mine doesn't. So now i'm going to recycle expensive oil and buy more new crush washers

Does anyone know what the green oil might be? And is Valvoline about the best conventional gear oil to go back with? It hasn't been submerged in water btw. Seen lots of people say water mixed in is green. Had no water in fluid, not foamy.

 

That's weird, sorry I'm no help. good luck!

 

Possibly cycle more through. I have the same year truck and switched to Mobil 1 syn with no issues.

 

I'd drive it more first.

2nd, you shouldn't need new crush washers if you do change it.

 

Mobile 1 75W90 is perfect.


Supertech is also dandy

 

The green oil was most likely lucas gear oil in the viscosity recommended for the truck. Its what I use and is green.

 

Thanks for the replies guys!

 

Lucas is what is recommended by East Coast Gear supply so I run it in the diffs. I can't say I'm a fan -- I've had a couple bottles where the additives are all settled in the bottom

T Case gets Mobile 1 or Supertech depending on what's on hand

 

I've seen some heavier weight oils that look green. Supertech 85-140 is green looking if I recall. You can get big jugs of Supertech gear oil for cheap. I use supertech in everything except my 5 speed tranny, which now gets Redline.

 

I've had STP/Coastal gear oils that are darker with green tint instead of honey colored as well

 

I read through East Coast's data on gear oils that @Wulf pointed out. The 85w140 they recommend makes sense.

 

I agree that more time with it (barring hearing some catastrophic sounds) is a good idea, and if further concerned do another change to cycle more new oil into the diff. I used redline 75-90 in front/rear/xcase and all is well.