So when I buy a used vehicle I always change the spark plugs and wires and I also change the air filter, just normal maintenance stuff. I did that the day I bought it and I just started keeping up with gas per tank mileage and it really sucked, even after changing the stuff I mentioned. It was about midway through the 2nd run of Valvoline Restore and Protect I started noticing that the mileage per tank going up. I’m no expert on anything but it had to be the Valvoline Restore and Protect making the engine more efficient as it got cleaner, just like it was when it was new I’m guessing.