I've been using Quakerstate Motor Oil for years now and i am still a happy customer. I am very glad i chose to use this oil when i started driving a vehicle. This oil really keeps your engine sparkling clean inside. I have never had a problem with deposit build-up in the engine. I would be led to believe that this is the best motor oil on the market right now. I have used a couple of different motor oils when i was trying to find the best and they would break down into sludge and not protect the vital parts of the engine. The other oils would leave deposits in the engine also causing a bad pinging or knocking sound. Quakerstate Motor Oil has never done this to my vehicles. I have used the higher mileage oil from Quakerstate also and am very pleased with the outcome of this. The higher mileage version Motor Oil just has a little additive in it to help coat the engine parts and keep them running like new. I have used the 5W30,10W30, and the 10W40. They are all great and will stand up to the test of any other brand. I can guarantee that myself.