Well the pinion seal is leaking on my car. The guy at the transmission shop said it could just be the rear end vent clogged. Where is this vent? Because the pinion seal shouldn't be leaking on a 40k mile car should it?

 

I would drive away from that shop so fast before I heard another word of wisdom from that guy. Pinion seals leak anytime & mileage, I replaced mine when the car was only three years old. A common problem and nothing to do with the vent on the axle housing.