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Red Line

Red Line 58204 Heavy Shockproof Gear Oil - 1 Quart

  • Based on 931 reviews
Condition: New
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Availability: In Stock.
Fulfilled by Amazon
Arrives Saturday, Jun 27
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Size: 1 Quart (32 Ounces)


Features

  • FULLY-SYNTHETIC FORMULAS - created from polyol ester base stocks, offer excellent lubrication under extreme conditions
  • ENGINEERED TO PROVIDE - the highest degree of protection and improvement of differential efficiency for better mileage, longer drain intervals, and less wear, exceed API GL-5 specifications
  • NOT RECOMMENDED - for most synchro applications due to the product's extreme slipperiness
  • POPULAR GEAR OIL FOR - Many performance racing applications like Sprint, Midget, Dirt Late Model and Quick Change Differentials, Detroit Lockers and spools, NHRA Top Fuel and Funny Car rear ends, most popular ShockProof product, many racing and specialty applications
  • WHY RED LINE - Established in 1979, Red Line Products perform & protect better than any on the market. No compromises

Material: Synthetic


Brand: Red Line


Package Information: Bottle


Liquid Volume: 32 Fluid Ounces


Item Weight: 1.7 Pounds


Brand Name: Red Line


Recommended Uses For Product: Gear Oil


Specific Uses For Product: Racing transmissions and transaxles, high load conditions, high-performance differentials


Item Form: Oil


Global Trade Identification Number: 49


Manufacturer: Red Line


Unit Count: 32.0 Fluid Ounces


UPC: 083522582049 083522582094


Number of Items: 1


Part Number: 57-6525


Model Number: 58204


Included Components: Red Line 58204 Heavy ShockProof Gear Oil - 1 Quart Bottle


Warranty Description: Limited Manufacturer


Item Type Name: Engine & Oil


Container Type: Bottle


Liquid Volume: 32 Fluid Ounces


Item Weight: 1.7 Pounds


Material: Synthetic


Part Interchange Info: 58204


Frequently asked questions

If you place your order now, the estimated arrival date for this product is: Saturday, Jun 27

Yes, absolutely! You may return this product for a full refund within 30 days of receiving it.

To initiate a return, please visit our Returns Center.

View our full returns policy here.

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Top Amazon Reviews

    • Great product
Size: 1 Quart (32 Ounces)
This is very good for Harley transmissions. Shifts smooth. Easy to find neutral.
Reviewed in the United States on January 3, 2026 by DanO
    • the best gear trans fluid made in my opinion.
Size: 1 Quart (32 Ounces)
Don't trust anything better since its made for racecar transmissions. I have used in my Harley FXSTC transmission for 10 years and its at 77000 miles and still smooth and quiet.
Reviewed in the United States on March 3, 2026 by Jeff Wynkoop
    • Highly recommended for Subaru open diffs.
Size: 1 Quart (32 Ounces)
Used this in my 1999 Subaru Impreza Outback Sport with noisy front and rear differentials. I threw some mobil0-1 75w-90 in each diff for about 1k miles to rinse things out. Just dropping the beat-up, dark diff fluid and going to Mobil 1 was a marked improvement alone. After running that sacrificial fluid for 1k miles, I drained it (and it was in much better shape, but still appeared QUITE DIRTY) and installed some Lucas full synthetic 75w-90 gear oil with about a half of the Heavy Shockproof quart going into the front and a half going into the rear diff. I put the Redline in first so it would mix better. Both my front and rear differentials are OPEN (not LSD; if you have an LSD, DO NOT USE this redline shockproof series). Immediately, I noticed that the diffs were notably quieter and that the car even accelerated and coasted more easily than even with the mobil-1 gear oil. I used the heavy shockproof because I'm in Florida and it never gets very cold here (it dips below freezing for a few hours, a few nights of the year, but only just below). If you are not in a southern state (FL, Texas, AZ, NM, LA, etc), I would advise selecting the lightweight shockproof instead. Overall, I'm extremely satisfied. If you have an open diff, or an air locker (anything but an LSD), you owe it to yourself to add a portion of shockproof to your diff. Quieter means cooler. That's always a good thing. Also, NEVER add this to any transmission. Even a manual. Your synchros will be permanently too slippery to work properly. ... show more
Reviewed in the United States on November 1, 2016 by TinkerGuy
    • Great product!!
Size: 1 Quart (32 Ounces)
Used in fxdl 5speed honestly it’s never shifted better.
Reviewed in the United States on April 1, 2026 by kenneth matteau
    • great stuff
Size: 1 Quart (32 Ounces)
basically liquid grease great for reducing gear whine in low power
Reviewed in the United States on November 18, 2025 by Amazon Customer
    • Best Transmission Oil
Size: 1 Quart (32 Ounces)
I am writing this review for the nay-sayers of this product. I have owned Harleys my entire life and Harley transmission have some noise issues going into 1st gear. This oil will stop that and the transmission will shift smoother than it ever has. Years ago I took my motorcycle into the shop for fluid change. I got home from the shop, which was around 70 miles and noticed the transmission was shifting differently. I checked the transmission oil and none was in it. They forgot to fill it up. The Red-line oil is so thick that it coated the gears and bearings and protected them from damage. If this would of been any normal oil. The bearings would of been damaged and the transmission would of needed rebuilded or even replaced. This oil saved me a minimum of 1,500 to a maximum of 8,000. I swear by this oil and will not run any other. ... show more
Reviewed in the United States on September 11, 2023 by Dave G.
    • Good but not great (for me and my bike) Came highly recommended to me.
Size: 1 Quart (32 Ounces)
I put this in my 05 Harley Fat Boy FLSTFI's 5 speed transmission. I usually use Amsoil's V twin trans fluid, but didn't have time to order any and heard good things about the Redline shockproof. After about 150 miles, I can say I prefer the Amsoil. For me and my bike, natural is easy to find in both. However, it noticeably shifts gears harder with a more pronounced clunk than I had in the Amsoil. I will be switching back to Amsoil. Overall, it is a good product but I like how my bike shifts smoother with the other product. ... show more
Reviewed in the United States on May 19, 2025 by Grant
    • Great stuff the pink milkshake
Size: 1 Quart (32 Ounces)
Best transmission oil for harley
Reviewed in the United States on April 3, 2026 by Zac

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