http://www.combinedfleet.com/guadoil1.htm
This is an interesting article, and filled with some useful stuff. The oil usage of the ships at various speeds, and what that means in terms of the way you should see forces in SH4. Yes, you can come upon a DD or 2 on patrol someplace alone, but they should NOT be steaming along at 34 knots. They need to cruise at a more sedate rate, and only dash when required for battle.
tater