It was recommended to me that I use 0W-40 Fully synthetic oil in my car (2002) by some on this forum and by a dealership. I went out and bought a 5 Litre jug of Shell Rotella T6 Synthetic 0W-40. When I got home I looked at it more closely and underneath the main label it says, "Heavy Duty Diesel Engine Oil." Are there two types of 0W-40: one for gas engines and another for diesel engines??? Is it OK to use this one in my car?