Haven't had any problems with them in Summer but I guess it isn't really that hot here in East Texas.

I think it has more to do with trying to keep operating temps close to a certain temp for optimal emissions. Every engine has a DESIGNED temp during operation to reach for least amount of emissions and optimal burn temp in cylinder and your tuner which in turn may impact the amount of fuel injected. Now whether it makes enough of a difference....probably not, too many other variables. The same engine is running in Alaska the same time one is running at the equator, do both need same treatment? Just being devil's advocate, I personally don't run one but have thought about a thin one or some kind of wrap to protect it.