in my 04 f150 i had my rear pinon seal fixed and new oil added by the mechanic. now 500km later i hear a whining noise from the rear of the truck that wasn't there before. is it possible they use different oil, that could cause the noise??? is there something else i need to put in with the oil?? or is just cold out? i've only had the truck for a few months and the noise started after getting the seal fixed.