Originally Posted by Big O Dave

As usual, Flash is right on... take his advice.

As an aside, and hopefully not too confusing for those of you who mix up transmissions with engines , Harley-Davidson Twin Cams are designed to have their motor oil run at 230F, and that's dino oil. Just mentioning this as a point of comparison. On my bike, I installed a H-D oil cooler and the thermostat on that cooler is set at 180F. Since installing it my oil temp has never exceeded 200F. I'm not too concerned about this being too cool... even though it's below the boiling temp of water, it is still hot enough to expedite evaporation. I prefer to have the extra margin of safety for longevity's sake (both engine and oil).

Back to Fords, if your motor oil is routinely in the 230F-240F range, then I would definitely recommend a synthetic, and Red Line is probably the best choice, especially since polyol ester based oils (of which Red Line is one) can handle the highest heat and leave the fewest deposits as a result of that heat, and the deposits they do leave are softer and less destructive that those left by PAO based oils.