Oil Cooler For A Shovelhead

I built my shovelhead in Oregon and ran Valvoline 60 Wt Racing Oil in both the engine and primary without an oil cooler in the Summer time and never had any problems. I then rode to Texas where it is hot most of the year, and I started hearing the top end start to rattle on really hot days. So I started asking around and it seems most people I ran into said put an oil cooler on it and start using 70 Wt. Harley oil.

We all know shovels run hotter so I did put on a cooler and went with the 70 Wt. Problem solved. Thanks, I'm old school so I don't know about the new synthetics, and from what I read here I didn't learn much ether, still your choice.