I have a small oil leak on the top of the engine. It looks like some oil is coming from between the vent tube and top of the valve covers and running down the rear valve cover. Easy enough to pull the tube and replace the gasket. I also think I may have some oil coming from the rear valve cover. I got new valve cover gaskets that appear to be a really thick rubber. I think I read where you can retorque the valve covers to get a better seal on the gaskets. Should I try that or just replace the gasket?