engine fumes entering through defroster duct
 

I have a bit of an oil leak which is dripping on my h-pipe. For some reason a significant amount of these fumes are finding their way up through my defrost vent on the dash. Where could the fumes be entering to get to the defrost vent?

I think you ar experiencing fumes and heat that are drawn in to the heating AC system. Check out this tech tip I wrote for a cure.

https://www.corvetteforum.com/techti...=241&TopicID=3

One common source is thru passenger side vent at kick panel....also ,after dark,shine a light inside car towards firewall and look from engine side for light leaks...