All newer vehicles have a white decal usually showing a belt routing diagram somewhere under the hood which tells the engine size. Also, some engines will have a stamp or piece of trim on top of the engine that says 2.3L or 1.8L or another combo of numbers followed by the "L" which means liters.
According to the 2006 Ford Focus Owner Guide ( for North America ) ( 5W-20 )
According to the 2002 Ford Focus Owner Guide : For the 2.0 litre SPI engine and the 2.0 litre Zetec-E engine : ( 5W-20 )
2.0l DOHC zetec 4 cylinder
sae approved 5w-30
well it calls for 5w30 for my 2000 dohc zetec engine.
What type of battery do i need for a 2002 ford focus
According to the 2008 Ford Focus Owner Guide ( for North America ) With engine oil filter change The 2.0 liter four cylinder engine takes ( 4.5 U.S. quarts / 4.3 liters of 5W-20 )
The 2013 Ford Focus has double overhead cam (DOHC).
The 2004 Ford Focus has double overhead cam (DOHC).
The 2009 Ford Focus has double overhead cam (DOHC).
The 2005 Ford Focus has double overhead cam (DOHC).
The 2003 Ford Focus has double overhead cam (DOHC).