Rislone 4784 DEF Crystal Clean™ Diesel DEF & SCR Emissions System Cleaner, 11.8 oz

I bought a used 2021 F250 with 75k miles. At first it was drinking DEF. I used 3/4 of a tank on a 900 mile road trip. I used this product on the first tank on my 5900 mile move to Alaska from Virginia. The first 3/4 tank of DEF, with the product in it, got me to Indianapolis, about 800 miles. The second tank I started using the Rislone DEF Treatment in every box I put in the truck, it got me to Mitchell, SD which was about 1000 miles and I used half a tank. About 1200 miles later I put 1 box of DEF in before I crossed into Canada, and stocked up on 3 boxes knowing I had about 3k more to go. Keep in mind, I'm hauling a 20ft enclosed trailer full of all my earthly possessions, and I have quite a few tools and heavy things. Something happened after that first 3k miles. I made it the next 3k miles and only used 1/2 tank. Now when I fill up it says 7500 miles to empty. I don't know if that's true, but it's been a long time since I've had to buy DEF.

Very good idea and quality.

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.

Trustworthy brand. Been using other Risolene products in my diesel truck,and have been pleased with the results.

This stuff is great. Had issues with DEF clogging DPF with crystals added this to DEF tank and light went off and hasn't come back on.

2020 Ram EcoDiesel throwing a P206A code. Looks like a DEF system issue. Daily driver, lots of hwy miles, 95K on the odometer, recently bought DEF at a truck stop, first time for that. Then the truck sat for a week while at a local body shop for front bumper work. Came home and next morning the dreaded check engine light. No performance changes, mileage still good. Used the Rislone DEF crystal clean and man o man! Poured entire bottle and brand new DEF in the tank, sat for 1.5 days and this evening I fired the Ole girl up and no check engine light nor codes! Life saver! Praise Jesus!

My 2018 gmc terrain diesel kept popping up telling me that the exhaust fluid is poor and that after 99 miles my vehicle will not go over 65mph. But every time it came up it said the same thing, it always said 99 miles. I use the premium DeF and I’m not sure how there was an issue. I purchased this product because it says it clears the fluid, also said it could take days of driving before the product fixes the issue. I’m a daily driver and spend a lot of time I town and on the freeway, I’m going on 2 weeks and still the warming comes up sporadically. It still says I’ve got 99 miles, I guess ima have to find somewhere or someone to flush the Def system, sucks cause I really hoped this DEF crystal clean additive would do as it advertises. :(

Not a big believer in "miracle" products but this one certainly performs as advertised, in my situation at least. Have a mini max that was throwing P2C7A and P14D9 code, both Nox codes. We assumed there was a problem at the DEF injector with crystals plugging things up. They suggest using the whole bottle, which I did, dumped the whole thing into a jug of DEF so it would mix, then dumped the whole DEF jug into the truck. Ran it for a couple of days, the service engine light went out, so I plugged in and checked for codes and they were gone. It has been a month and I haven't seen any lights and the codes have not reappeared. A $20 bottle is certainly better than a trip to the dealership.