AF1

Does anyone run Mobil 1 75w-90 ...the manual states 80w-90 I can only find 75w-90 in mobil 1......Think this will be fine for long trips?

Yosmany

I just replaced my diff fluid and asked the dealershiop if that was ok. They said yes. That most of the really good synthetics are not a straight shot wieght.

Amsiol 80W-90

Mobil 1 75W-90

So you'll be alright. 75W - 90 means that it can act like a 75 W to a 90 W.

WATRD

75w90 is fine anywhere you would use 80w90. It's just slightly thinner when it's cool. At operating temperature, both are are similar weights and will act the same.

toybox

I'm confused a little because I keep seeing 80w-90 talked about for the 4th gen's but my Owner's manual says 75w- 90. Is the 80w - 90 a personal preference or did you guys read it somewhere that that is what is recommended for 2003's???

I just ordered 7 qt's of 75w - 90 from amsoil to do my diff's and transfer case so I hope that I am right.

Yosmany, amsoil has 75w-90.

mt_goat

My manual says to use 80w90 for the rear diff and 75w90 for the front (ADD), but I use Mobil 1 75w90 in both.

AF1

Thanks everyone........Makes me feel more at ease.

foxtrapper

75w vs 80w is splitting hairs. The significant number is the 90. That's the one that tells you the viscosity of the oil at operating temperature. The w number doesn't even actually have an SAE spec. It just tells you it's thinner when cold then a straight 90 oil. It does not mean it pours like an 80 or 75.

A synthetic gear oil can be a very good thing. There is a lot of parasitic power loss in thick gear oils. Going to the much freer flowing synthetics can give a discernable performance increase and fuel mileage increase.

That said, make sure your seals are in good shape. Synthetic oils do a great job of creeping past seals and such. A damp spot becomes wet, and a leak becomes a river when going with synthetic oils.

sn0w_m0nkey

i've been running mobil-1 synths since about 2001 in my 99'er. no probs so far, loving it, my truck is a happy truck.

AF1

I flushed my tranny and filled with Vavoline max life.....says for Toyota. In a post a while back you mentioned adding LubeGuard...I have a bottle of LubeGuard and need to know if adding to Maxlife would be to much friction modifiers? or would it be ok? Thanks

AF1

Sorry about that reply...wrong post...

JSharp

I've had M1 75W-90 in both diffs, the transfer case, and the manual transmission for the last 2 years. It works fine and shifting in cold weather is noticably better...

Nic

I put Amsoil 80W-90 in the rear differential and 75W-90 in the others, but it's just because I could. Amsoil had both weights.

Before I went with the Amsoil, I was going to buy the "Toyota" brand gear oil. The guy at the dealership service counter told me they just put regular stuff in. He didn't even know what brand. He said they use 75W-90 in everything including the rear. He said it didn't make a difference.

X-AWDriver

I just switched to Redline fluids in the gear boxes and expect no problems since that was all I ever used in my Eclipse for 8 seasons of racing.

Nic

Yeah, on that note, I should have said earlier that I too switched to Redline MT-90 in the transmission because of the notchiness in shifting with the Amsoil. It seems the Amsoil is too slick for the synchronizers-So they say. I don't have a clue about how transmissions work.

It helped, but did not completely cure the problem.

There are some threads on this subject if you do a search.

Y2Krunner

a tad bit off topic here, but my manual says to use SAE 75w-90 in the front diff and SAE 90 in the rear. whats the difference there?