In a 2004 Honda Element, the engine control unit (ECU) is located under the dashboard on the driver's side. Specifically, it can be found behind the kick panel, near the steering column. To access it, you may need to remove the kick panel cover and possibly some other components for better visibility.
My 2004 Honda uses 5w-20 . Use a good quality detergent oil listed for gasoline engines.
The 2004 Honda Pilot has a V6 engine.
The 2004 Honda Odyssey has a V6 engine.
The 2004 Honda Civic has an inline 4 engine.
The 2004 Honda Accord has an inline 4 engine.
The 2004 Honda Insight has an inline 3 engine.
The 2004 Honda CR-V has an inline 4 engine.
The 2004 Honda Insight has a 1.0 L base engine size.
The 2004 Honda Pilot has a 3.5 L base engine size.
The 2004 Honda Odyssey has a 3.5 L base engine size.
The 2004 Honda Accord has a 2.4 L base engine size.
The 2004 Honda Civic has a 1.7 L base engine size.