i agree that senthetics are better than conventioal oil, but when you have a motor that leaks, burns, and consumes oil and you change it every 2-3k miles it actually doesn't make sence to me to use synthetic. I use the 20w50 cause i beat on my cars and want that extra protection. especially in the hot summer months the 20w50 helps keep the oil pressure up where it needs to be. and with high milage engines i wouldn't use anything else but castrol.