My 2007 Dodge Ram 1500 has been seeping oil from the left valve cover gasket for over a year. I had the truck in the shop twice and had the gaskets replaced. They will stop losing oil for a while then start again. Always on the left side. Is it possible the valve cover is bent or warped? I checked the bolts and they are tight. I wanted to get some advise before buying a new valve cover. It's a 5.7 Hemi with only 250,000 miles lol.