Hello all,

I have a 2004 Mazda3s 2.3L AT. I did an oil change the other day - usual stuff as always, drain all oil, change out the cartridge filter (after soaking it in new fresh oil) and install the new rubber rings that come with the filter, button it all back up, pour in the recommended amount of oil (synthetic 5w-20 4.25 quarts). Start it up and check for leaks - all is good and motor sounds good and smooth. Clean up the shop supplies and tools, head in the house and change clothes and get ready to head to buddies house to watch Monday Night Football. After doing a couple of things in the house, finally head out about an hour after changing oil. Get into car, turn her over and head out. Noticed a slight knocking noise coming from engine and I dismiss it as a small amount of oil starvation and figure it will go away soon enough. Climb on highway and the knocking noise gets much louder. Turn around and head home. No football tonight. Get home and listen to location of knock. Find the location, shut down the engine and pull out a couple of spark plugs to take a look. Chunks of valves. Sad day for the gipper...

So, did a little more digging, pulled the valve cover and found some more oil starvation problems and a cylinder that was caked with black deposits. The engine shes a goner...

So, I need to replace the engine, and my question (finally!) is will a 2005 Mazda3 engine drop in a 2004 Mazda3? (both 2.3 and AT) If I understand correctly, 1st gen Mazda3's are from 2004-06, so a further question would be could a 2006 Mazda3 engine drop in a 2004 Mazda3? Any help and wisdom would be appreciated!