I've actually been looking into those sandwich types as well. They aren't super common, but can be found. I think this is probably the easiest ways to do this mod, although there are many other ways.
Honda has used them on quite a few engines including the CRX HF, Civic VX, and Insight (as well as a few others). I went and checked this morning and sure enough, I have one slapped to the block on my Insight.
For others not familiar with these, in the picture the silver thing you see that the oil filter is screwed to is not the block, its a device that circulates coolant through it. Thus, as the oil is flowing through it, it gets heated up.
So, I was like 'cool, I'll get one for my Prius'. Unfortunately, that won't really work. Honda uses a M20x1.5 thread on its oil filters. Toyota like many domestics I'd assume uses a 3/4"-16 thread. I searched ebay and was able to find one of these for a Tundra, but I haven't searched a ton. I assume that other manufacturers have similar parts, its just a matter of finding them. FYI if you're looking, they're typically referred to as an 'oil cooler' as they will cool the oil with the coolant when the oil gets warmer than the coolant. Thus, I believe its also used on the Integra and Prelude engines as well.
Here are a few more pictures of the Honda ones to give an idea of what they are and how they work. I'm really surprised we haven't talked about these before on EM. I searched and was only able to find one really old thread where it was mentioned, but not really discussed in any depth.
