Which oil cooler is the best?

Spartan 1771

This past spring I installed a Mishimoto Oil Cooler with the basic sandwich plate. The cooler works very well, but it's a bit of an issue on cold mornings. The temp has a hard time getting up to 185. I need to devise a cover for the cooler and I was actually considering wrapping it in tin foil and then using a small piece of duct tape to hold it in place. Is this a terrible idea?

Thanks for the help in advance.

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~Rob

-DD Air Guide, Stillen G3 CAIs, 63mm Throttle Bodies, Motordyne M370, Berk HFCs, FI TDX CBE (non-res, CF), Sprint booster v3, Ecutek Dyno Tuned, and the list goes on...