The top-performing Serck that BillA tested is an oil cooler. They are generally designed for minimal pressure drop, and often employ internal turbulators. So, cost aside, are oil coolers a better choice than heatercores?
As far as cost goes, Setrab makes a line of
high-performance oil coolers, which can be
purchased on eBay for about $40-$50 (comparable to the Serck: 11x5x2, 16 plates).
ps. Any ideas on what would be the best way to clean oil out of one of these?