This is something that has confused me for a long time as we know heat is the main enemy of engines.... I see posts about adding or upgrading transmission coolers all the time; However no one, even google is not able to produce any evidence of an "external oil cooler". Apparently they exist and they are not standard issue, the reason for this, at least on my 2000, above the oil filter, there are 2 ports (I assume an in and an out) and I have heard some people in passing, refer to an oil cooler. This is not the best pic, I had posted it in reference to the oil leak problem I am having in my 5.3L but it looks like there is a port on top of the casing that the oil filter is attached to (facing up). If anyone could provide some insight as to what an oil cooler(I know what it is, but specifics), with links, photo's and potential part numbers, that would be great. Thank you.