97 F-250 Diesel Serpentine belt question

[Sumatra]

Hi,
Question about the pulleys and so..
Are all the pulleys should have free play w/o resistances?
I noticed the vacuum pump pulley spins some what freely(after removing belt) but with some resistance. Feels like half turn goes easy but other half does turn slowly then speeds up. Is this a normal thing with this pulley.?
I noticed some degradation on the flat surface of the belt in one specific spot similar when you run a piece of wood or metal through a belt sander..
Thank you.
F

 

[blacksnapon]

Welcome to the site. The resistance shouldn't be a problem, remember, it is a pump. When in doubt on a belt, change it.

 

[Sumatra]

Ok thanks for the feedback.
On another note, at 200k miles on this truck. What would you recommend for engine oil. 10w-40, or other viscosity..
I bought the truck 5 months ago and I know is due for oil change but wanted to make sure I use the appropriated oil
Thanks again..
F