Changing single oil cooler to duel

[HankAz]

Yup, a little history. I ordered mine as a 600. Last year I put in a recon and didn't have any problems. This summer I started getting red shut down lights at the top of grades. I took it in to Cummins to get it checked out. I had just had issues with the X Y shifter and thought the guy at Kenworth changed something in my parameters.
He comes back and says it's the oil temp that is setting it off. He also thought that a 600 should have a duel cooler. So that was when I started reading here on Rawze's forums. I changed the oil thermostat but it has cooled down outside now so I'm not having the problem any more but I'm going to change it at Christmas time when I'm off to a duel cooler anyways.
Oh, and mine is in a T660.
Hank