hey,

ive recently bought an RS turbo fiesta, its a one owner from new car, and every service its had castrol RS 0w/40 oil...

now ive been looking into it and im pretty sure 10w/40 is the correct oil for the car

heres where my problem comes in... do i use 0w/40 because thats what its always had? or shall i start using the 10w/40 as reconmended?

what would you do?

cheers.