Be very wary of third party warranty companies. When we purchased our 2001 Dodge Caravan (new) we opted for a 100K mile extended warranty that the dealer didn't bother telling us wasn't a Chrysler warranty. The warranty company went bankrupt, abandoning millions of policies (and making national news a few years ago), but not before denying each and every claim we tried to make.

If you are dead set on saving a few bucks up front, *read the fine print*, i.e. exactly what the warranty does and doesn't cover. You may have to perform (and be able to document) maintenance that is more aggressive than what the manufacturer recommends or else be in breech of the policy's terms.

Perform due dilligence on the warranty company itself. At very least, check them with www.bbb.org. Look for unresolved complaints about unjustly denied claims.