What oil for a 2005 vauxhall combo 1.3?

Up to 2005 build, 10/40 semi synthetic.

From 2006 Build, 5/40 fully synthetic long life oil.

To work out build date, read the 10th digit of the chassis/frame/vin number. (starts WOlO or VSXO depending on age.)

if is a letter, or a number 5 or under, it's an up to 2005 build.

If it's a 6 or higher, it's a 2006 onwards build.

Failure to use fully synthetic oil in 2006 onwards Vauxhalls can cause engine damage, and also failure of diesel particulate filters (if fitted).