Red Line 57904 75W90 GL-5 Synthetic Gear Oil for Hypoid Limited Slip Differentials - 1 Quart (2 Pack)

If you are aren't familiar with Red Line automotive lubricant products -- be informed that most knowledgeable mechanics consider it to be the best line of petroleum products available. My cars are all currently FWD, but I have a long history of ownership and maintenance on 4-speed manual transmissions and RWD differential units. Presently, I use this gear oil in the differential of my Yamaha shaft drive motorcycle. My recent experience . . . The original Yamaha factory gear oil had been changed to Valvoline Synthetic at a few thousand miles. At about 16,000 miles on the odometer, I had noticed a little bit of audible gear while decreasing speed down to a stop. I figured it was time for a gear oil change and this time installed the Red Line 75W90 Synthetic Gear Oil. The whine immediately disappeared. Would it have disappeared if I had used any other oil? Probably. Or maybe not. Either way, I really like knowing I have the best lubricant available in the gear unit. I'll should also mention. This stuff is super slick, and claims to reduce heat dramatically and increase efficiency (gas mileage) a few percent (we'll see). It's so slick that the manufacturer suggests that for limited slip applications, a limited-slip additive is probably not needed to eliminate chatter (I recall in years installing a rebuilt Chrysler 8 3/4 posi unit and had to do exactly that -- put in an additive to prevent chatter -- so Redline is claiming I possibly wouldn't have had to do that using their lube -- an interesting claim). UPDATE: After putting about 6,00 miles on this Redline in the differential (motorcycle), I've "touch-tested" regularly, and can report with confidence that this stuff absolutely reduces operating temps. A lot. Even after extended high speed/summer temperature use, the differential temp never got much past "warm to the touch". With the original Yamaha gear oil, it got HOT. This is great stuff.

This is known to be a great product and it's served a Genesis Coupe well thus far. I'm not a fan of the bottles, which just don't need to be so tall, and get in the way when you're commando crawling under the car. Plus, little pumps won't attach to the threads. But at least the oil is top notch. So much so that I won't dock the product for atrocious packaging.

Works as described

Delivered in proper time, will be first time using this product for a differential, I have heard great reviews and product quality for the RedLine 75w90 use on Mercedes Benz.

I used this on a 2024 Nissan Frontier with an open (DANA) rear differential. This differential fluid has an ester/pao base with a very robust additive package. It has a more viscous consistency and provides more of a "cushion" for the gears and bearings inside a differential. The fluid itself has a slightly red appearance and you can actually smell the esters in the fluid. Redline does a really good job with their formulations and base oils.

This is excellent gear oil. Been using it for years.

My Mazda MX-5 ND limited slip differential was incredibly noisy with the fluid the dealership had. Red Line was recommended by several owner forums so I thought I’d check it out. Wow, what a difference. The rear is quiet and the chirping I had when accelerating from a stop is gone. Absolutely worth the time, effort and expense to upgrade.

The rear diff on my '07 Tacoma Sport was so rough I thought it was toast. I changed the oil with this Redline 75W90 GL-5 and it works sooo much smoother. I'm guessing the previous owners filled the diff with regular gear oil without any limited slip additive. With this Redline gear oil it runs smooth as silk... like I have a new diff! No special additives needed. I'm so happy I went with this product. I bought 4 quarts and used just over 3 to fill it. The only issue I had was the bottle opening is not a standard size... slightly smaller than a normal quart opening. It will work with quart hand pumps (SP) though, just be careful to hold the pump in place on the bottle and not spill any. I plan on using this same oil in the transfer case and front diff as well. You will need a 6$ crush washer kit for all the drain/fill plugs. Includes both diffs & T-case.

Mejor aceite para mi diferencial

Little pricy but good stuff. Oem oil weight grade

Red Line Gear Oil consistently delivers superior performance under high-stress operating conditions, making it an optimal choice for both professional and enthusiast-grade mechanical applications. Engineered with advanced synthetic formulations, this product offers exceptional thermal stability, shear resistance, and long-term protection across a wide range of gear systems. In real-world application, the oil has demonstrably improved drivetrain smoothness, reduced operating noise, and contributed to extended service intervals—resulting in reduced downtime and maintenance overhead. Its performance in high-load and high-temperature scenarios reinforces its reputation as a category leader in gear lubrication.

デフ特有のガリガリ音も少なく効きもとてもいい感じです。 夏場やサーキット走行するにはもっと固めのでもいいかもしれませんが街乗りではとても十分です！

Great lubricant, lasted in the car for several years.