Hi TomCa. I drove mostly at 55 mph on cruise control. I think there are a lot of unhappy truckers out there due to my speed or lack thereof. I switched to synthetic yesterday and ordered the hi-performance kit ($265). The salesman at K-N supposedly said to expect a 2-3 mpg improvement and more HP. Hmmmmm, I hope so. At Walmart I purchased a window stick-on compass, a 3 outlet expander for the cig lighter, and a clock-temp (in and out) also a stick on (tape). I'm like a kid on Christmas morning.