Why are airplanes white?

Another aspect of the issue is painting things in the engine
compartment:

http://www.sacskyranch.com/paint.htm

This source concurs with an earlier poster in stating that it matters
whether the object is warmer or colder than its surroundings. The
author also points out that what the paint is made of matters: since
most of the energy transfer at temperatures we're interested in occurs
via conduction a paint's insulating properties may be more important
than its color, especially for outward energy transfer, where there's
almost no reflection of radiation at the component/paint interface.