Carquest EP 90 GL-4 as a transmission fluid?

[Elkins45]

Carquest sells a gallon of 90 grade GL4 gear oil for $16.99 they specifically say is for manual transmissions. My Scion specs 75w-90. Other than difficulty shifting in cold weather is there any reason I shouldn’t use a straight 90 grade oil in my transmission? A 75w-90 ostensibly spends most of its time as a 90 anyway once the transmission warms.

 

[Lubener]

Use what is specified. Does the manual specify GL-4? It will be very noticable shifting gears in N.Ky in the winter with a straight 90.

 

[930.engineering]

Use what is specified. Does the manual specify GL-4? It will be very noticable shifting gears in N.Ky in the winter with a straight 90.

THIS.
Hard shifting in winter doesn't help your synchronizers.

On a sidenote: A straight SAE90 doesn't even necessarily
have the same KV100 as a typical 75W-90 GL-4. It's often
thicker even when hot (and transmission oil commonly
doesn't even reach 100°C, so you'd better look for KV40).
.

 

[Elkins45]

Use what is specified. Does the manual specify GL-4? It will be very noticable shifting gears in N.Ky in the winter with a straight 90.

The manual specs GL4 or GL5.
I could go down to Walmart and buy three quarts of GL5 gear oil from any number of brands, including their house brand for dirt cheap, but everybody tells me not to use a GL5 fluid even if the manual says it’s OK. At least this stuff says it’s intended to be a transmission fluid. I suppose I could cut it with a bit of synchromesh to thin it out a bit.

 

[RooflessVW]

I'd use Honda MTF. It always shifts buttery smooth and it's inexpensive at the dealer.

 

[bullwinkle]

Pennzoil Synchromesh-you can thank me later!! Tested for over 80K in my Scion xB! Even though your toaster is a 4-slice & mine is only a 2-slice...

 

[slacktide_bitog]

If you want to stick with 75w90 and prefer to buy locally, the only MT-suitable 75w90 GL4 sold on the shelf of a US store is Liqui Moly 20012

Otherwise, you can get the Valvoline 75w90 from fittingsgo (Canada) or Castrol Syntrans Multivehicle (now called Castrol Transmax Manual). Rock Auto used to have the Valvoline but stopped selling it. Another option is Miotorcraft XT-M5-QS, which is made by Castrol.

 

[brianl703]

There are local stores that sell Redline MT90. They tend to be independently owned racing and repair shops. You can find them using the locator on the site here:

Red Line Synthetic Oil. Dealers

Red Line has a reputation with racers and enthusiasts alike for creating products that perform and protect better than any on the market. No compromises.

www.redlineoil.com