I know this topic is discussed regularly, but after I change my oil, especially from Dino to syn, there's definitely a noticeable difference in the sound, feel, etc. Everyone agrees, right? Quieter, smoother, etc. I had Havoline Dino in for 6100 miles (6months) and put the QSUD back in. The Havoline was very black upon exit. Of the 6100 miles I'd estimate my commute is one way 9 miles with 7 interstate miles, and I road tripped a total of about half of those miles (road tripped meaning at least an hour drive at 60+ mph). Most would probably say I should've analyzed my oil to see how much life was left, but the oil and filter together cost me $12 and my new QSUD and filter was $23. So I don't see why I'd pay $15-30 for an analysis. Except that I kind of want to because I'm a geek like that. But the oil is now at the bottom of the pit of my local WalMart service center. They always freak out because I keep my oil in a red gasoline jug. "OMG it's in a gas jug! We can't recycle gas!" "Um, it's oil. The gas jug was just cheap and easy to fill with old oil. Never been used for gas." "Well, it's not our policy to take it in gas containers." "Ok, I have a 5 quart jug in my car, empty. I'll just fill that 3 times and bring to you from the parking lot. Deal?" "Ok, I guess we can dump it this time."