Summer+ Formula Diesel Fuel Additive: Each Quart Treats up to 640 Gallons of Diesel Fuel (1 Quart (Treats 640 Gallons))

I had previously given a 1 star review due solely to shipping concerns. Sean from optilube reached out to me and went above and beyond to alleviate those concerns. This really is a company that cares about the customer. My business makes a negligible impact on optilubes portfolio or bottom line, yet they reached out to me and provided the type of service and customer appreciation you simply do not find with large businesses. As far as the product, its the best on the market. And I have tried them all. I have a 1994.5 powerstroke and both xpd and XL cut the engine noise by almost half. Even my 10 year old daughter said "your pickup isnt as loud as it used to be". I wont buy any other additives but optilube, their product is the real deal, not a snake oil.

I'm not sure if the truck makes more power or torque or fuel milage. My truck idles often that is not good for long life. if it idles more smoothly with less noise and starts quicker I believe it's worth using. It has a 475 H.P. 1999 3406e Cat at 575,000 untouched miles. I'm switching to semi synthetic oil, I'm trying to keep it untouched till some time much later.

.this stuff really works and I get about 51mpg hwy using opti lube on my 2010 vw golf tdi I drove from Sc to Nj all highway miles I got 602 miles before I seen the fuel light gauge then drove back from Nj to Sc with out using opti lube I got 523 miles before I seen the fuel light all highway miles driving 70 mph on Air conditioner on 3.city driving I get 35mpg combined 40mpg I hope this help anyone looking to buy a diesel additive for they truck or car

I've been using this for months in my 2011 Silverado 3500 and it's been great. I can almost instantly hear the difference when I add it to a tank without treatment. I keep the entire bottle in a toolbox along with a STABIL bottle that I cleaned out. The stabil bottle is PERFECT for adding into the tank after a fill up and I really recommend the company to start using these bottles. I have an exergy filter to protect my CP4, but hopefully it's never needed with this additive. Currently at 128K miles on my LML

I have no idea how well this product is lubricating my engine parts but I love the price.

Bought this for my deep well motor , stopped exhaust smoke and also improved run time. This stuff works great, I highly recommend

Excellent value and quality. I generally use hot shots or clean diesel products, these seem to be as good if not better in a concentrated formula. So the cost per treatment is very reasonable. I find it makes my sprinter run smoother and maybe a 1-2 mpg improvement?

So far compared to XPD it is lasting much longer and way better value for money. Don't forget I live in PHX so moisture is a low concern. I have noticed higher oil temps ( but summer temps just made a jump). Also a little more black smoke on take off. Again....higher summer temps could explain. I have a bottle of XPD so when the summer + is gone, I will switch back and see what happens to the puff on take off. And report back. BTW. Tuned and deleted exhaust only. Egr in place S&B filter. 6.4L Powerstroke.