Customer Ratings & Reviews

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.

I have a ram with the 5.9 cummins engine. It had developed a rough idle and an intermittent clicking from the injection pump. I tried several diesel fuel treatments, but nothing really changed. I thought I'd give this a try. I treated a full tank of fuel at the clean up dosage. After driving about a 100 miles, the idle had smoothed out. After about a 1000 miles, the click was gone in the injection pump and mileage was up to about 21 mpg. I now use it at the maintenance dosage every time I fuel up.

Même s'il fait -30C ça démarre pareil pas branché, merveilleux! De plus je n'ai pas à badrer avec l'eau dans le diesel ou sa gélification... IMPECCABLE!! Incontournable en hiver! De plus ça prend soin de la pompe à injection!! Sans compté sur le petit surplus de puissance! Ram ecodiesel 2015 180 000km

Have been using the product for about a year now. Haven't had a gell up in any of my machines and gotten better fuel mileage.

Crossing multiple state lines and fuel quality in question this stuff will help with condition, lubricity and increase fuel efficiency.