455Olds:
Oil Cooler or no Oil Cooler?
I've read pages and pages of internet sludge regarding this topic, and it seems the arguments go both ways. I had thought it was a no brainer. Apparantely not. Several articles I read stated that in a marine environment, there is no need for such a cooler. Unless your oil is truly heating up or breaking down, is it really needed? Should I add one to my boat?
I had one on it before my latest rebuild, but the spun bearing pushed shavings everywhere. I'd be damned if I was risking a shaving still be inside the cooler. I'm getting only 25lbs now though, could this be part of the problem? not having a cooler will not cause the low pressure you're describing because your cool idle pressure is too low to begin with at 40 lb. then dropping to 25 when it heats up (what I would consider a normal drop in pressure difference between cold and hot). 40 lb though should be the least you see with hot oil at running rpm. 20-30 at an idle (hot) maybe but it should jump as soon as you touch the throttle back up to 40 or preferably higher if things are right.
To accurately answer your question whether you need an oil cooler, you need to know your oil temperature (gauge). otherwise you are guessing in the wind.