I've been watching this site for over a year and I finally decided to register and follow the advise of others regarding oil and car maintenance. Well, on my Ford Mustang GT (2000) I decided to try Castrol 0W-30 and a K&N oil filter in my Stang. My car has only 23K on it and the oil/ filter was changed every 3K with Ford 5W-20 and a Motocraft filter. The old Ford oil had 3.5k and was quite clean. The Castrol (German) oil has made my Stang drive smoother. It idles smoother and revs smoother. There is quite a difference! I also went back to the original Motocraft filter cause of some of the negative reviews on the K&N. I'm going to run this oil for 10,000Km or 6,250 Miles and give it a oil analasis. Do you guys recommend this? I've never ran a car over 3000 miles and the same oil before.