I took some much needed vacation days (heading up to Nashville for the Nascar race). So I`m bored at home and started thinking how bad I wanted to tinker with my car! Sooooooo,I had some Valvoline 10W40 dino sitting around and well,out goes the 20W50 and in goes the 10W40. How do you say night and day diference????? Feels like a different car! Engine is so smooooooth and quiet! It felt really weird when I broke the rear tires loose accelerating in 3rd gear! Did the 20W50 really rob my car of that much power? If I`m really brave,I may drop down to their 10W30 next oci. Don`t know if I`m brave enough to try a 5W30 though,since the factory fsm says not to,although there`s a guy on one of the Z32 forums that uses Pennzoil dino 5W30 in his twin turbo Z and swears by it.