Baldwin designed a PF52 replacement just for the turbo Buicks, i.e., the antidrainback valves actually work. I had to order at least a case because parts stores don't sell them around here. With tax and shipping included they came out to around $6/per. They're the best I've seen. The Wix valves work about half the time which puts them in second place. Its nice having instant oil pressure EVERY start with the Baldwins.