Can my cooler be more temp efficient?

I've got the 10 gal MLT (cheap and easy). However, if I infuse at exactly 154 I'll be down to 150 by the end of the hour. I'm not preheating. I just overheat the strike and hit my mark. How can I stop loosing those 4 degrees? Or should I just not even worry about it?

Thanks

A two-inch thick piece of foam insulation cut to the shape of the cooler and laid on top of the mash works wonders. You lose nary a degree!

Well I really cinched down the lid of the cooler tight. Usually I'm pretty reserved about doing it too tight because I have a digital thermometer and I run the cord for it out between the lid and the cooler. Now I haven't lost a degree in 30 minutes. I'm strong at 154. I don't know what that's about. I guess it made all of the difference. It wasn't exactly put on there loose before or anything.

This is what flyangler is taking about. During last weeks brew, I lost one tenth of one degree over an hour. You can just insert your thermo right thru the insulation.

You mentioned that you don't preheat but that is one the best things you can do to help maintain your temperatures during the mash. The reason is because your cooler will sap heat away from the mash as will the grains. If you preheat the tun, leass heat will be sapped by the cooler during the mash and you will be better able to maintain your mash temps. I preheat my mash tun (52 quart cooler) by heating my mash water twenty degrees above my mash temp and adding it to my cooler and closing the lid. I let it sit with just the water inside for ten minutes and check the temp. By then, the water should be just a little over my strike temp and I then stir it while checking my temps until it reads my strike temp then I add my grains to the water and mix them in being careful to break up any doughballs that might form. After this, I close it up and mash away. Doing this, I lose only a single degree over the course of my mash.