Laminova is a Swedish company that makes excellent water-to-oil heat exchangers:
oil-coolers - The Laminova heat exchangers - Laminova
These suckers are WAY expensive. Think $300 and up. Available in the USA under the Mocal brand name as well.
Ford contracted with Laminova to have them produce a cooler for use in their heavy-duty applications (taxis, police cars, etc.) from the 1990s, and they turn up in junkyards from time to time. While the internals are the same, the plumbing is specific to the Ford application. Laminova coolers have the water entering from each end, and the oil from the top and bottom. Ford wanted oil lines entering and exiting at one end. They use special flex hoses which snap into the cooler and are thus a bit user-hostile, as it makes it harder to adapt it to another application.
The housing on the Ford unit is cast, rather than the thin sheet aluminum on the normal coolers, and thus seems much more robust.
In practice, the cooler is mounted right at the base of the radiator on the ever-present Ford Crown Victoria. The short oil lines lead to an adapter mounted on the 4.6 block.
They are functionally identical to the $300 units but can be had for $25 or so from a junkyard. Here's a typical one:
I bought several of these and intend to incorporate one into my Pantera...someday. I need to ditch the stock rubber oil line hoses and have the cast housing threaded to accept A/N fittings. Packaging constraints will require me to mount the unit near the radiator, which means looooong oil lines back to the engine. I will probably try to fab up hard lines rather than stringing hoses for five feet. But then again, the long hose solution might just be easier to live with.
I'll have to use a simple sandwich adapter on the block for the oil in/out lines.
Like I said...it's a 'someday' project. :laugh:
This type of cooler probably won't do a terrific job of knocking off a LOT of oil temperature, but it's certainly a start. At least as useful is the fact that it warms up the oil when the car is first run, as the heat is exchanged the other way.
For more information, let Google be your guide....