Rislone4784 DEF Crystal Clean™ Diesel DEF & SCR Emissions System Cleaner, 11.8 oz

As always, I'm skeptical when it comes to product performance—but this one? Amazing.I never owned a diesel until I bought my '21 GMC HD2500 Duramax. I love it, but man, diesel engines demand preventive maintenance. You can't wait for things to break—you’ve got to stay ahead of it with products that help reduce or even prevent issues.This particular product is excellent.Since the day I bought my truck, I’ve had nonstop problems with the DEF tank sensors sticking. Sometimes it would show full when I knew it wasn’t, and other times it claimed to be half empty right after a fresh fill-up. Totally unreliable.And what did the dealer say? “It’s inadvertent.” That word should be banned—it’s just an excuse to ignore a real problem.Let me tell you—this product works. Period. And it worked fast, too. Absolutely amazing.

Kept having DEF related issues and cleaned up my tank/system quickly. L9ve how the bottle was designed to pour in the tank without a fuel. Will be buying again.

Excellant product. I highly recommend it.Instead of my truck telling me I needed DEF fluid it threw a code and immediately started to count down to miles left before a reduction in speed. Then I remembered I is DEF that was old. When I looked online I found a YouTube video explaining this product. I put a half bottle dose into the 5.5 gallon DEF tank in my 2016 GMC Canyon and within a day the engine light went off and I was back to normal. I put the second half of bottle in the next DEF fill up. Since then I ran NJ to Florida twice with no issues.

Cautious user. Truck sat most of Winter, so really my cause & effect with the DEF crystallizing. Cleared my DEF code 3 times. What a pain in the ass. Filled my DEF tank 100% on 2017 Ram & ran to Colorado ~ 1000 miles. Dilution & keeping the DEF tank >50% with this first treatment seams to be working. I bought a DEF injector valve on Amazon & will change it out. The challenge with this little valve replacement is the possibility of damaging the threaded mounts on the exhaust tailpipe. PB Blaster & 10mm box end wrench!! Seems to be a good product! 😀

Cleans theft system and gets rid of problems. I have used this on a Peterbilt and a Freightliner

Got the dreaded “limp mode” message on my Ram diesel. Tried this product 1st. Did not make a difference in 100 miles. Turned out to be a bad coil on the DEF injector, which cannot be fixed with this product. Rislone is a good product, but not for use in this case.

I have a RR Sport I rely on this. If you have a diesel engine and don’t drive a lot of long distances or high speeds, you need this so your DEF filter doesn’t clog.

I added a dose of this to my tank as a preventive measure to keep everything in good working order. Never had a problem with anything prior to using this stuff. The "Poor DEF quality" warning light was displayed soon after i added this to my tank. After running the truck until DEF was around 1/2 tank, I topped the tank off with DEF and the warning light went away on its own and I haven't seen it since. I never noticed any actual problems but my Duramax L5P didn't like it. It could have been the DEF that I added when I added the product--i have no way of knowing. I've always bought Peak BlueDEF and never had a problem except when i mixed it with this.