Customer Ratings & Reviews

I bought this diesel truck in 2017 new off the lot in Houston, Texas. Ran 500 miles break in with the factory oil then changed to Amsoil. First tank of diesel had this additive and I've used this additive with every tank of diesel. Just went over 211,001 miles and have never had any issues with fuel, that crazy CP4 fuel pump or any injector issues. Truck runs like a new one even with the miles on it today. My mechanic tells me that the only reason I've not had a pump failure is because I've been using the additive.

Perfect for my F-250 7.3!

210,545 miles NO CP4 failure because of this product! Diesel mechanic tried to sell me on a "disaster prevention kit" until he heard I've been using the product from the first tank of diesel.

I use this all year round in my truck, tractors and mowers. I have never had a single problem. Don't use #1 in the winter I just use 4-in-1.

Just starting using Amsoil 4-1 Diesel fuel treatment based on social media recommendations. Have gone through 3 tanks, every other fill up, and seems my Cummings 6.7 gen-4 with 120k is running a little smoother. However no news is good news in this case.

Product works as should

Great product! Noticed better cold starts, fuel economy, and power.

This is a great all in one product. One bottle works for all my needs including the annual trip to Wyoming in freezing climate.

My truck got some bad fuel (water) and my injectors suffered, I kept using this 4in1 to help lubricate the pump and injectors in hopes of extending their life, was constant injector performance faults. Took about 1 month of continuous use but the faults are gone. I also started to use this product on all my construction machines, especially like that it has the anti gel additive, it’s helped me a few times.

I have only used a single bottle so far. However, having said that it works. I live in a very cold climate and it is doing its job.

Great product I fill like my truck runs better on this and I don’t have to worry about the fuel gelling on me.

Never have had any problems with injectors clogging up. Can rely on consistent power.

Four stars only because I wasn't able to rate it any lower than -20 degrees Fahrenheit. Diesel was unblended #2 with a sudden cold snap arriving and used the additive without starting or running issues on a ungaraged diesel over a three day period.

The cold starts fuel additive works well i use it in my 2021 gladiator, 2001 dually duramax and my farm tractor it helps all 3 of them in the cold weather i highly recommend this product.

Really good for my diesel engine love it truck loves it

Noticeable improvement in acceleration. Recommend for routine usage.

Seems to have helped the tractor I put it in.

Love your products. Thanks

As always, best products around. It doesn't get better than this.

The diesel fuel additive works great, but it's difficult to empty the bottle in your fuel tank as the neck of the bottle is too small. You need a funnel so you don't tip the bottle bottoms up to get the additive out.