>
>
> Now I'm thinking I want to install a temperature-operated switch and a
> fan to force air through the cooler when the van is working hard but not
> moving very fast. Like climbing up long, steep desert grades at 4,000
> rpm in first gear.
>

That's why using this kind of oil cooler is so effective.
http://www.setrabusa.com/fanpacks.html

bob