Synthetic/non-synthetic gear oil

I was recently considering changing the front and rear diff fluid as well as the transfer case. I called two dealers to inquire about purchasing Toyota gear oil, but neither sold it. One dealer told me specifically not to use synthetic and that any 75w90 would be fine. The other dealer told me that I could use either. This dealer also said they don't even use Toyota gear oil but rather Mopar synthetic should they perform the services. I don't know if it matters, but I have an 04 SR5 2.7 with 100,000 miles and have never changed any of these fluids. Any insights would be appreciated.

 

I had the same problem until I called my local Pep Boys and Auto Zone, they both said it would be listed in the owners manual. I cant recalled what kind it said to use but I do know that it does not matter whether you use either its just your preference.

 

You can use synthetic....nothing wrong with it. I used Mobile 1

$34 75W-90 Synthetic Gear Lube - 1 Quart (Pack of 2)

75W-90 in my 96 Tacoma. The Tacoma had about 70K miles on it when I changed and I had that truck until it had 110k miles and wheeled the snot out of it. Never had any problems.

 

I have read on this forum several times, that if you have the limited slip rear differential--Using any kind of synthetic gear oil is all bad. I have routinely used conventional

$34 75w-90 Synthetic Gear Lube - 1 Quart (Pack of 2)

75w-90 (just to be safe) in the rear with an lsd additive and have had no problems with the clutch plates slipping or chattering. I'd love to switch to a synthetic if there was one out there that was known to work well with the lsd. Just too many bad reports from people using the synthetic. If anyone has found a synth. that works well in this lsd, please let us know.

Oh ya, BUMP for this old thread!

 

Not full syn, But I used $6 a qt Valvoline Dura blend 80w-90 in my LSD for two changes, no LSD additive either. Works great, no slip or chatter.

 

the toyota dealerships I usually go to only uses pennzoil products for the diff and trans cases.

 

I switched to Royal Purple about 2 years ago. I emailed Royal Purple for oil recommendations before doing so. It seems to help with a bit more power once warmed up but in low temps (35F and lower), shifting can be a bit notchy for a few miles.