

⚙️ Shift smoother, last longer — the gear oil pros swear by!
Red Line 50304 MT-90 is a premium 75W-90 GL-4 manual transmission lubricant designed to protect gears and extend synchronizer life. Its friction-optimized formula ensures quicker, smoother shifts even in cold conditions, while being safe for brass synchros by avoiding harmful reactive sulfurs. Trusted since 1979, this 1-quart bottle delivers reliable performance for GL-1, GL-3, and GL-4 applications, making it a must-have for professional-grade manual transmission care.






| ASIN | B000CPCBEQ |
| Best Sellers Rank | #6,096 in Automotive ( See Top 100 in Automotive ) #9 in Gear Oils |
| Brand | Redline Oil |
| Customer Reviews | 4.9 4.9 out of 5 stars (2,849) |
| Date First Available | July 20, 2005 |
| Global Trade Identification Number | 00083522503044 |
| Is Discontinued By Manufacturer | No |
| Item Form | Fluids,Oil |
| Item Weight | 1.7 pounds |
| Item model number | 50304 |
| Liquid Volume | 32 Fluid Ounces |
| Manufacturer | Yukon Gear & Axle |
| Manufacturer Part Number | 50304 |
| Material | Brass |
| Model | MT90 75W90 GL4 QT |
| Number of Items | 1 |
| OEM Part Number | 50304 |
| Package Information | Bottle |
| Product Dimensions | 9 x 4 x 4 inches |
| Recommended Uses For Product | Lubricant,Lube |
| SAE J300 Viscosity Grade | 75W-90 |
| Specific Uses For Product | Lubricant for manual transmissions and transaxles, Prevent corrosion, Enable smooth shifting, Provide gear protection |
| UPC | 083522503044 |
| Unit Count | 32.0 Fluid Ounces |
| Viscosity | 75W90 |
A**M
Miracle Juice!
I put this in a 2002 Chevy Tracker (rebadged Suzuki Vitara) with a 5 speed stick transmission and lever operated transfer case. The factory specification calls for a 75w90 GL4 gear lube in both but a previous owner had put GL5 rear end gear lube in them. GL5 eats at the "yellow metal" brass/bronze used in the gear synchronizers in the transmission and transfer case. As a result of this the transfer case would not shift into low range and the 5 speed stick was very tricky to shift. Hard shifts, having to force it into gear, being stiffer when it was cold, just overall not smooth. I was worried because a friend with a Jeep had a similar occurrence and ended up replacing his whole transmission because it became unshiftable and wouldn't hold gears. Read a review of this Redline and it's specific use for manual transmissions. Figured it couldn't hurt and put it in the transmission and transfer case. IMMEDIATELY it was smoother to shift just sitting in the garage with the engine off. I backed out of the garage and was able to promptly push it into 4lo for the first time since I have owned it. Worked great and I backed right up a small hill without any trouble. Several weeks later it's shifting better and low range is back. I will say the transmission was obviously damaged and the transfer case is still not smooth going into low range but I CAN go into low range now and the transmission is definitely smoother. I can only imagine what this stuff would be like in a transmission in better shape than mine. It's not cheap but considering how hard it is to find GL4 rated 75w90 anymore (I bet your local parts store doesn't have it or has a few quarts at most) I'd highly recommend this Redline product.
M**W
Worth it
Used in my 2002 7.3 with a ZF6. This stuff is awesome transmission is quieter and shifts smooth. Just wish Redline used a bag instead of the hard bottle. It is a real pain to fill the case but worth it.
D**N
Good Stuff
Good stuff!
R**D
FANTASTIC FOR TOYOTA MANUAL
I have a 2015 Scion XB (Toyota) manual transmission and changed it a few weeks ago and used that Ultra 1 GL-4 and my manual transmission started having clunky gear shifts. I just changed it to Red Line MT-90 that's actually recommended by Toyota and what a difference. Immediately felt the shifting smooth as silk. Oh well, live and learn. Buy what's recommended by the mfg because they know what they are talking about. My fault.
M**N
Best for Tacoma 5spd (2003)
2003 toyota tacoma Xtra Cab 4x4 - 2.7L - 5spd Changed all the gear fluids 2x-3x in my 180k mile taco over the past 2 weeks. I let the tcase & trans drain for a couple hours (hot) & it took about 1.3quarts in the tcase and a little over 2.6quarts in the transmission. You could get by with 4 quarts, but I like the feeling of pumping it in until it dribbles out (which took 4quarts point something total; so i'd order 5quarts). And here is what I noticed: 1) An average of about 20miles worse mpg on an entire tank of gas compared to synthetic GL5 fluid (in manual transmission and transfer-case) (355miles @ 15.5 gallons vs. 375mi @ 15.5gal) 2) Much smoother shifting in manual trans compared to other older gl4 formulas & newer gl5 stuff. The clutch contains a larger friction zone. Now whether this extra smoothness actually causes more wear or not I have no idea. I'm pretty sure, people worried about copper or brass in your syncros or tranny / t-case need not be worried with the gl5 fluids. Most gl5 fluids say safe for brass on the bottle. Having said that - there's an obvious difference between safe for 100k miles and safe for the 400k i'm trying to hit. EDIT: changed my mind. Worth 5 stars. Saw the Walmart fluid after 10k miles. $#%& the Walmart GL-5 especially in hypoid gears. I'm serious... don't be stupid like me. I probably took 10k to 50k off my rear diff life (which I expect 400k out of) by running walmart fluid for 10k miles @ 90 to 105mph. If you're not going above 75mph or towing you might be ok. A word about fluid change intervals just from what I've seen in my truck (toyota recommends 30k miles for all fluids): Rear Diff - 30k is likely a tad long for the rear diff (20-25k feels better) - but I regularly drive thousands of miles at 90mph. If you aren't towing, driving about 80mph, or doing other stressful differential (for hypoid diffs) driving then 30k is probably ok. @ 70k-150k miles the rear diff fluid was black as hell and saturated with fine particulates Front diff - I barely use 4x4 (maybe 10x a year for 10 miles at a time. There was pretty much absolutely no wear on the front diff fluid in 70k miles. transfer-case - noticeable mechanical wear of oil (splashy - not thick like syrup), minimal particulates, but still good protection in 70k miles (change whenever) transmission - particulates and mechanical wear, decent wear on the fluid in 35k miles (stick with 30k-ish) Hope sharing that experience helps. Best of luck. P.S. - look at your power steering fluid (suck out the reservoir with a turkey baster & put in new stuff - drive & repeat). Ran 110k to 165k on the original ATF in the power steering system. That was risky.
C**Y
Good oil for manual transmissions
Works great in AX-5 transmission. Make sure you have a pump, as the bottle doesn’t fit in tight places.
M**L
Changed out the gl-5 transmission oil that was in my 2006 tacoma to this oil. With the old oil the truck shifted rough and slow, would grind into 3rd gear every shift, felt like a worn synchro. With this new oil the shifts are smooth and it just pops right into the gear. 3rd Gear goes in perfectly 95% of the time, sometimes get some feedback of the synchro when I put it in but its minor compared to before. Would Recommend it for any vehichle especially with brass synchros, but if your owners manual says gl-5 only stick to that. Great oil just pricey might be possible to find it locally for cheaper.
M**S
Viskas gerai.
A**A
Used it in my safari dicor. Awesome performance. but the price is on higher side.
P**K
Ottimo lubrificante, il cambio ora é fluido e non si impunta piu.
A**A
愛車用に使用 指定が75w-80のAPI GL-4 なかなかAPI GL-4のギアオイルは少なくMT-90にたどり着きました。 冷間からの入りもよく温まると更に良いです。 コスパも良いほうなので今後はこれ一筋で行こうと思いました。
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2 days ago
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