This post is by Brian McGahan on OSPF type 5 E1 vs E2 routes. It explains in detail how the OSPF state machine works and busts a few myths on OSPF metric calculation. Remember that OSPF prefers E1 over E2 regardless of metric. A common misconception is that E2 does not use cost to ASBR when calculating metric. Read the post to understand why this is wrong.