Is thick oil bad for or hard on the oil pump or any of the engine parts? I hear some people say that thicker oil is good for extended highway driving,and then hear others saying thick oil is bad for engine parts(oil pump for example)and that the thinner the oil,the better. I noticed that on older Z`s(it was on a 91 I was once looking at),there was a Nissan factory sticker under the hood saying to use 10W30 in the colder weather and then switching to 10W40 in the hot months. But,in my 96,it says 5W30 in the cold and 10W30 in the hot in my owner`s manual with no mention of anything thicker than 10W40.
