Hi Martin,

The Focus model year change was around 2011, so that affects the change intervals. And you didn't tell us which engine size, so we've given you the lot here:

For the newer Focus:

1.6 TDCi, all power outputs manufactured up to July 2011: change every 140,000 kilometres or every 10 years

2.0 TDCi: all power outputs: change every 200,000 kilometres or every 10 years 

For the older model:

1.6 TDCi - split into either 200,000km and 10 years or 240,000km and 10 years and you'll need to check the engine code to see which is which:
 - 240k: codes G8DA, G8DB, HHDA, HHDB
 - 200k: codes G8DC, G8DD, GPDB/GPDA/GPDC 90hp, G8DE/G8DF 109hp and the Econetic models

1.8 TDCi: all power outputs: change every 200,000 kilometres or every 10 years 

2.0 TDCi: all power outputs: change every 240,000 kilometres or every 10 years except for the 133hp model with engine code G6DG; that's 200,000km