Rislone 4784-6PK DEF Crystal Clean™ Diesel DEF & SCR Emissions System Cleaner, 11.8 oz (Pack of 6)

This cleared all my low quality DEF alerts. I also noticed my truck is back to using the original amount of DEF as when I bought it. Definitely cleans the lines and DEF heater. Amazing product

Works! Got me off the side of the highway. 2019 Ram 3500 Dually. 6.7 diesel. Probably just a band aid but it worked. Along with their other diesel additive. The red bottle for diesels. The best additives I’ve ever used.

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.

I used this in DEF tank since I had been geting P20EE codes regularly. I could see crystalization around pour tube, cap, etc. I put this in, then I got the dreaded Poor DEF Quality message and P20EE code again. Then it went away. A few miles later, back again. Then after a few days. maybe 75-80 miles, no more codes. Took a long trip of 650 miles, plus local driving, code and DEF message have never appeared again. Seems to do the trick. I also add in the Rislone maintenance DEF fluid product. Seems to all be working as intended.

Used it, couldn't tell any difference but maybe that's because mine wasn't that bad. Didn't improve anything, Didn't make anything worse.

Why did you pick this product vs others?:I bought this in March for my 2014 Ram ecodiesel. My def tank fill sensor stopped working and the dealership wanted to charge me $4k for a new tank (buying just the $5 dollar sensor isn't an option). I put this in and bought a device to delete the check engine code so the truck wouldn't go into limp mode on me. So yesterday (6-25-25) about 3 months later, the gauge just shot up off the spot it had been stuck. Apparently I was right and there was a crystalized buildup on the sensor. I would recommend anyone with the issue try this before you drop the money for a new tank 👍

DO NOT ADD. I bought it to clean my after treatment system because i had a code where it said o had possibly put bad DEF in the tank. Reading up online that crystals might form in the SCR, i found this product. Hoping that it would clean up the system, as it states, it actually contaminated my after treatment system and melted (YES! MELTED) my DOC and SCR and ruined my DPF. (See pics). Dont cheap out just buy better quality DEF. Its cheaper that replacing these after treatment parts.

My DEF level sensor was going haywire and wasn't showing the correct level in the tank. Sometimes it would say empty when it was full, or full when it was running low. I was about to make an appointment with the shop to get it fixed, when I discovered this product. After reading about DEF crystallization and residue issues, I suspected my problem might be from crystals that had formed on the level sensor in the tank. With nothing to lose, I filled the tank with DEF and overtreated with two bottles of this treatment. Despite the tank being 100% full, the gage showed the tank 3/4 full. We took an 800 mile road trip a few days later, and the issue resolved after about an hour on the road. That was 2 months ago, and the problem hasn't returned. This will now be part of my maintenance routine whenever I change my oil. Highly recommended!