Saw a post on this a while back but I think I am looking at a little different scenario. I have a 468 BBC and I run Valvoline straight (4 quarts) 50 Wt. with a bottle of Lucus Oil Stabalizer. I believe the oil pan is a 5-6 quart oil pan. I change the oil every three times I go out to the lake after it gets fairly black.
Problem: Fresh oil and first trip to the lake I am running around 80 lbs. of pressure. As the day progresses I notice that the pressure starts to drop to around 60 lbs. (Possibly to the thinning of the oil) Second trip I am running around 60 to 70 lbs of pressure but after a hard run say about 3-5 min at 5600 RPM I notice it has dropped to about 30 to 35 lbs of pressure. It never falls below this or hits zero like the last post related to this issue. It just gets really low especially when I let off the gas. I assume thats from the oil rushing to the front of the oil pan?
Solutions: ??? Possibly a bigger oil pan? Different type of oil?
All responses are appreciated. Thanks to all who respond