I just did the first oil (Mobil 1 5w30) and filter (AC/Delco) change on the Cadillac CTS I recently bought for my wife. Couldn't believe that the filter is a canister type. Just like really old vehicles used. Very strange to me, but it's got me wondering why GM went with this design. Is it to make the changes easier or is it supposed to filter better somehow (doubt it). If anyone has a clue about this, I would appreciate it.