This is the inportant bit.
Summary
The vehicle must be serviced every 18,000 miles.
However, if the mileage travelled in the last 12 months was less than 6,000 miles, an engine oil and filter change must be carried out.
If the mileage travelled in each year is more than 6,000 miles but not enough to reach 18,000 miles in 24 months, an engine oil and filter change must be carried out after 24 months.
See separate guide for esseesse versions.