Frank;
It shouldn't make any differance which way you run the
oil threw the cooler. Did you install a remote
oil filter at the same time, or change the lines? The filter has a check valve in it. Did you change from a standard filter to a hi-performance one. The standard filter usualy has just a flap for a check valve that most
oil pumps can overcome. Some filters have a steel check ball that the pump cannot unseat during reverse flow.
Poorboy