Been using it for years . First heard about it at the drag races. VEry surprised , and even made skeptical , by the great price. Price has managed to stay low throughout the years. Have tried many other expensive,even professional, products. This one always seems to work. Stopped wasting money , and started saving it instead. Used it countless times on cars and trucks , new and old. Have even argued with auto parts employees over it, when they try to sell me seafoam or STP (on sale). Ive even had one say that its too strong and will cause my seals to dry /crack……. Nver happened . I used it for the whole lifetime of my Nissan,as a fuel addititve , and as a solvent to clean my injectors directly through the intake. always felt the diffrence immediately. Never ever felt like i wasted my money and got robbed (unlike others). Never had no engine trouble. Sold it at 280000 miles going strong. Repaired the valve cover seal , my friend (long time mechanic)thought i had a rebuilt engine because it was so clean inside. I have amazed and made many other believers of friends, by helping them tune up/maintain there car using berryman b-12. First they are skeptical, think its too good to be true, waste of money. Once they experience the difference in power. Smooth idle. Car even starts and feels and sounds different. Ive had some older cars feel renewed instantly. Now everyone is constantly wanting to use it on there cars, or asking me how to do it again. They all want to know so they can help other people/themselves with there car maintinance. First and only mandatory , and consistent product on my list for tune up supplies. Other items can be substituted , But for Berryman there is no close substitute. Thanks to Berryman for offering such a quality product and keeping it affordable. Helps many people , especially when times are tough to keep there vehcles running great!