I've heard lots about the Lucus products, both good and bad. One warning about this product is it's THICKKK, almost like pouring out a bottle of honey/snot.So you have to go slow or it'll be messy, you have to wait for the little trail to finish.I tested this on my 2014 GMC Sierra, slowly adding half a quart instead of a whole. It was something I decided on my own, but I had the engine warm and running, I wanted to mix it into the oil as quick as possible. Being as thick as it is, I was worried pouring a big blob of it in then starting the engine would clog stuff.The results surprised me, the engine ran quieter and smoother. It wasn't a huge difference, but enough to notice. Starting it up after a night of sitting was much quieter too, it sounded like it was just easier to spin over.Then I tried this on my girlfriend's 2017 Jeep Renegade, doing the same routine except I poured a bit in then started the engine and then off, repeat until I got about half a quart in the crankcase.The same results happened. It ran quieter, quicker to start, and there was nearly zero rattle noise while driving. And I don't know how, but the throttle felt quicker. It was the most annoying part of driving that car, it always felt like a slug. It wasn't amazingly fast, but it felt more like how a little car should accelerate.Overall, it is a awesome product! And if I could extend the life of my vehicles using it, buying a big bottle every couple years is still way cheaper than buying a new car!