Red Line MT-90 75W-90 Transmission Fluid – 1 Quart

Red Line MT-90 75W-90 Full Synthetic Gear Oil – 1 Quart

You know that fight you have with second gear on a cold morning? That clunky, notchy feel that finally
loosens up once the car’s good and warm? A lot of the time, that’s your gear oil talking, not your
transmission. Red Line MT-90 is the fluid people swap to when they’re done putting up with that, and
it’s the kind of change you feel on the very first drive. Your synchros start engaging clean, your cold
shifts quit fighting you, and that grindy notch either disappears or gets close to it. It’s sold by the
quart, so grab however many your transmission takes.

Whatever You Do, Don’t Put GL-5 In Your Transmission

Here’s the mistake people make all the time, and it’s a costly one. They grab whatever gear oil’s on
the shelf, usually a GL-5 meant for the rear diff, and pour it into their manual trans. Don’t do that.
GL-5 is loaded with sulfur additives, and those additives eat brass and bronze, which is exactly what
your synchros are made of. So you’re slowly killing the very part that makes your transmission shift,
and you won’t feel it happening until your shifts go to garbage. MT-90 is a GL-4, no aggressive sulfurs,
totally safe for your synchros. And it’s got the right grip to it, not so slick the synchros can’t
catch, not so sticky they drag. That balance right there is why it shifts so nice.

Cold Is Where Cheap Gear Oil Falls Apart

Most gear oils feel fine once everything’s warmed up. The trouble is the cold, they thicken up like
honey overnight, and that’s why your first few shifts on a freezing morning feel like you’re stirring
concrete. MT-90 stays flowing all the way down to -49F, so when you fire it up and grab first in the
cold, it goes in clean instead of putting up a fight. If you deal with real winters, this is the part
you’ll notice and appreciate the most. And it doesn’t thin out on you when it’s hot either, so you’re
covered at both ends.

Where MT-90 Belongs (And Where It Doesn’t)

This is the fluid folks reach for across a ton of gearboxes, Honda, Nissan, Mazda, Mitsubishi, Toyota,
VW and Audi, the Lotus Elise and Exige, Mendeola boxes, even Atlas transfer cases if you’re building
something for the dirt. It covers GL-1, GL-3, and GL-4, plus most of those finicky synchromesh fluid
specs, and you can mix it with whatever’s already in there, petroleum or synthetic, if you’re just
topping off. One thing though: keep it out of any differential with hypoid gears. That’s not what it’s
built for. This is a transmission fluid, so that’s where it stays.

What You Get

• Red Line MT-90 75W-90 GL-4 full synthetic gear oil, 1 US quart
• Safe for brass and bronze synchronizers, no reactive sulfurs
• Right coefficient of friction for smooth synchro engagement
• Pour point of -49F for clean cold-weather shifts
• Viscosity index of 200 for stable performance hot or cold
• Satisfies GL-1, GL-3, and GL-4 specs and most synchromesh fluid specs
• Compatible with petroleum-based oils and other synthetics
• Not for use in differentials with hypoid gears

Specifications

• API Service Class: GL-4
• SAE Viscosity Grade (Gear Oil): 75W-90
• SAE Viscosity Grade (Motor Oil): 15W-40
• Viscosity @ 100C: 15.5 cSt
• Viscosity @ 40C: 82 cSt
• Viscosity Index: 200
• Pour Point: -49F / -45C

Note: Red Line MT-90 75W-90 GL-4 full synthetic gear oil, sold individually in 1 US quart bottles. A
GL-4 formulation without the reactive sulfurs found in GL-5 oils, making it safe for brass and bronze
synchronizers. Correct coefficient of friction for smooth synchro engagement in most manual
transmissions. Pour point of -49F for clean cold-start shifting and a viscosity index of 200 for
stable performance across temperatures. Satisfies GL-1, GL-3, and GL-4 specs and most synchromesh fluid
requirements. Compatible with petroleum and other synthetic oils. Not for use in differentials with
hypoid gears. One quart per order.