which Rotella T

[GZ250]

Today I went to Walmart to actually see the Rotella oil cans. Until now I have only read the posts about that. They have Rotella T 5W-40 (blue 1g can) for $19. It is full synthetic and it says on the can that it is for gasoline engines also. They also have Rotella T 15W-40 (white 1g can) for $10.50 but on the can it does not say that it is for gasoline engines. It only mentions diesel. On Shell website they mention this oil as multigrade and it is also for gasoline engines. Is it only for big gasoline engines or any gasoline engine (small as GZs)?

There is a difference of $10. So which type is really good. The difference is not that much. I change (oil + filter) every 3000 miles. I use my motorcycle everyday, does not abuse but I drive fast.

Actually I am asking to compare the two types with the standard Suzuki brand. On the scale of 1-10, where is 5W-40 and where is 15W-40. :??:

Thanks a lot.