Don't worry about the low pressure at hot idle. Most modern "idiot light" switches turn the warning light on below 7 lbs. of oil pressure, but there's just not a gauge to let us see how low the hot idle oil pressure is going. If the gauge is not dropping to zero at idle, and/or there's a knock, don't get too concerned about a low reading. Heavier oil will stress the distributor gear and drive tang on a cold start, and thick oil won't lube well until it warms up a little. Personally, I'd run 15W40 or a straight 30 weight high detergent oil, but opinions about oil are like "noses" everybody's got one, and some of them are pretty "smelly"!
Jerry
