I'm servicing a 2006 Freestar with the 4.2 engine. The spark plugs that came OEM on this engine was a Motorcraft SP504 platinum (AGSF34FM). The manual and online part# only reference a copper plug, the SP506 (AGSF34N).
Strangely, for older model Freestars (2004-2005) with the exact same 4.2 engine, they reference a Motorcraft platinum SP486 (AGSF42FM).
Based on this spark plug decoder, it seems the newer SP504 is just a colder heat range plug:
http://jimsprojectgarage.weebly.com/motorcraft-spark-plug-information.html
So does anyone know why Ford changed the recommended spark plug part # for 2006 on the exact same engine? Why did the plugs that came factory on this engine (SP504) not even come up as a choice?
I just put in the older higher heat range plug, the SP486 and just want to make sure ir's ok. It's a HUGE PITA to do plugs on this van.
Strangely, for older model Freestars (2004-2005) with the exact same 4.2 engine, they reference a Motorcraft platinum SP486 (AGSF42FM).
Based on this spark plug decoder, it seems the newer SP504 is just a colder heat range plug:
http://jimsprojectgarage.weebly.com/motorcraft-spark-plug-information.html
So does anyone know why Ford changed the recommended spark plug part # for 2006 on the exact same engine? Why did the plugs that came factory on this engine (SP504) not even come up as a choice?
I just put in the older higher heat range plug, the SP486 and just want to make sure ir's ok. It's a HUGE PITA to do plugs on this van.