I had my 2001 Nissan Frontier pickup in because of an oil leak. They told me it was the valve cover gaskets. Cost me right at $500 to get them replaced. Truck is still leaking oil. Not sure what to think at this point. They did't clean the engine off to determine if it was still leaking, figured maybe it was residual from the original leak, but been long enough to determine it is something else, maybe not the valve cover gaskets to begin with. What would you suggest I do? Pretty disappointed with the service. Spent a lot of money for no results.