I have a 1996 4Runner with 120k on it. I am going to be changing the tranny fluid and I want to use the Redline MT-90 which is synthetic. Should I have any concern about using synthetic on my high mileage truck? I have mainly heard in regards to engine oil that the synthetic oil has a tendancy to find weak spots in seals due to its finner properties. Does that also go for tranny fluid? Currently I have no leaks on my truck.

 

its fine.... my truck probably has around 200k+ miles, and when i can afford it, im going to be using GM synchromesh in the tranny

 

good ˟˟˟˟.

Use it, just check the fluid level in a few weeks. You shouldn't regret it.

 

Yeah, I use BG full synth in my tranny. Thing works like a dream (and I'm hard on my poor truck).

 

If your engine has been properly maintained and has no signs of leaks you can start using synthetics. I would suggest Amsoil XL7500 after doing the Amsoil engine flush thing.

 

Are you refering to engine oil or tranny fluid? I think as far as engine oil goes I am not balsy enough to switch just because dino has been working and I think I will stick with it. But as far as the transmission and differential, I would like to get those on synthetics.

 

if your truck has a bunch of miles, synthetic engine oil can only benefit you. IMO. I run Amsoil synthetic everything and I have 97k miles.

 

...you said 120k...my bad

 

Nolan, I swithced over to Amsoil for my transmission and diffs/t-case when I bought my truck. Still using dino for the engine. It had 110,000 miles on it when I bought it. I have not had any problems.

I did, however, drain the Amsoil from the transmission and switch over to the Redline MT-90 since my shifting was not that great with the Amsoil. I have been pretty happy with the Redline in the transmission and I guess the Amsoil is doing OK in the diffs and transfer case.