Red Line 50304 MT-90 75W-90 GL-4 Manual Transmission and Transaxle Lubricant (MTL) - 1 Quart (4 Pack)

Red Line MT-90 is a top-tier synthetic gear oil that delivers noticeable improvements in manual transmission performance. I used it in a high-mileage 5-speed and immediately felt smoother shifts—especially in cold weather. It quieted down some minor gear whine and made engagement feel more precise. The GL-4 rating is perfect for transmissions that need protection without the aggressive additives found in GL-5 oils, which can be harsh on yellow metals like synchros. The viscosity is ideal for most import and domestic gearboxes that spec 75W-90, and it holds up well under heat and load. If you're chasing better shift feel or just want to treat your transmission right, MT-90 is a solid investment. It’s not the cheapest option, but the performance and protection are worth every drop.

Highly recommend using this in Porsche 944 transaxles. I have used this in 4 944s and each time the noise has gone down and cold shifting has gotten smoother. I also just tried it in a suzuki sx4 that had a transmission that made noise at idle and it has removed the noise and greatly improved the shifter feel.

I put this in my 2005 4.0 V6 6 Speed MT tacoma and it removed the small grinds going into gears. Definitely worth the extra money!

Smells like gear oil. Moves like cold syrup. Red Line has always been a quality product. Used in the transmission of my 1991 Toyota pickup. Shifts like butter! Quiet just like before the change. Used with hand transfer pump without issue.

100% great product, transmission on my 1998 Jeep shifts smoother than ever. Seller also helped me with a shipping issue with UPS! Thanks

Works as described

Excellent manual transmission gear oil We notice easier the Toyota Tacoma is much easier to shift gears in cold weather. Previous brand oil required much slower shifting with considerable resistance on cold morning below 40 degrees. GL4 is much safer to use in transmission with brass parts than GL5 because GL5 additives are often chemically reactive with brass causing unnecessary wear.

Quality, helps shifting, protects transmission, reduces noise, easy to pour in and its lubricity and greasiness is perfect for older and newer vehicles. Lasts longer than stock fluids too

Shifts very smooth in my 2009 mazdaspeed 3

1994 Eurovan 5 speed shifting as it should again. Shipping speed wss good. Packaging was good. It was bit pricey but there are cheaper alternatives. You get what you pay for.

I used it for a classic car manual transmission.

Great product

Would be five stars but took way too long to get to me.