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The obvious is that the jacket (you know, the bit around the cylinders that coolant flows past to cool the oil and cylinders) is already a heat exchanger.
Insulate the oil pan which will reduce temperature loss via the momentum of the vehicle moving (or just to the ambient low 'merica conditions).
The jacket isn't as efficient as the plate heat exchanger in the OP, but that will also function to cool the oil (essentially bringing both mediums to the same temperature, and if left in would heat the coolant up, thus forcing cooling to be required too - i.e. your oil will also only reach up to whatever your cooling system is over engineered to cool to).
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