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Availability:
In Stock.
Arrives
Oct 20 – Oct 21
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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
Container Type: Bottle
Liquid Volume: 32 fluid ounces
Item Weight: 1.7 pounds
Material: Synthetic
Part Interchange Info: 58204
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 Fluid Ounces
UPC: 083522582049 083522582094
Number of Items: 1
Number of Packs: 1
Included Components: Red Line 58204 Heavy ShockProof Gear Oil - 1 Quart Bottle
Item Type Name: Engine & Oil
Model Number: 58204
Part Number: 57-6525
Warranty Description: Limited Manufacturer
Frequently asked questions
If you place your order now, the estimated arrival date for this product is:
Oct 20 – Oct 21
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.
To initiate a return, please visit our Returns Center.
View our full returns policy here.
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Top Amazon Reviews
Size: 1 Quart (32 Ounces)
I recently purchased a 2010 Softail Cross Bones with 1600 miles on it. I did a 3 hole oil change on it and this is what was in the transmission. Prior to changing the fluids I put about 200 miles on it and noted the shift was smooth and crisp. I went ahead with the Amsoil for the primary and engine, but ordered this Red Line for the transmission because I was so impressed with it. After about 1000 or so miles on it so far, I couldn't be happier. I'll continue to use it in the Cross Bones and may start using it in the Road King Special and the Softail Slim.
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Reviewed in the United States on September 16, 2026 by Amazon Customer
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.
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Reviewed in the United States on September 11, 2023 by Dave G.
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
Size: 1 Quart (32 Ounces)
Best oil u can use for harley granny beats dealer price
Reviewed in the United States on July 26, 2026 by nurse
Size: 1 Quart (32 Ounces)
If you know, you know. Best at what it does.
Reviewed in the United States on September 16, 2026 by James Lamartiniere
Size: 1 Quart (32 Ounces)
Don't let the color scare you. It is deep red and smells like 90W gear oil. Used this product to change the tranny fluid in my '03 Road King. From the very first test ride the change is noticeable. Shifting is quieter and more smooth. Neutral is right there, no fumbling for it. At speed the whine may be not as loud. Only running this for a couple hundred miles so far with no problems.
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Reviewed in the United States on June 3, 2021 by BenjaFord
Size: 1 Quart (32 Ounces)
Use the Redline Heavy Duty Shockproof in my 2007 Harley Street Bob. The transmission runs smooth as silk on this stuff. Makes a noticeable difference compared to other gear oils on the store shelves. Prior to Redline heavy duty shockproof, I had run Lucas and Royal Purple gear oil in my Harley tranny...both were fine but I'm not going back to them after hearing and feeling the difference of the Redline in there. Can't beat it...highly recommend. It'll make your transmission run smoother, cooler, and quieter. Well worth it, don't bother with other gear oil and definitely do not run Syn-3 in the transmission. That stuff is trash.
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Reviewed in the United States on June 8, 2019 by ChrisWNY
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.
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Reviewed in the United States on November 1, 2016 by TinkerGuy