Well...over a week later I'm told that the oil that was in the engine was Castrol Edge 5w30, which the inpector says is the correct oil. The engine specialists carrying out the repair work aren't so sure.
I'm sure that I've always used 5w40. If I do a search on castrol's site and use their Lubricant advisor I get to the model page
http://www.ew2.lubesinfo.com/login.asp?sc=1156 and quickly get confused.
I can narrow it down to two different models:
Golf 1.9 GT/GTI PD (QG1 - 96/110kw)
Golf 1.9 GT/GTI PD (QG0/2 - 96/110kw)
The one labelled QG1 is stated to use 5w30 whereas QG0/2 states 5w40. Anyone know how I tell which model mine is? Or, is the site suggesting that both oils are suitable?
I noticed that the product info for the 5w30 doesn't mention PD engines, whereas the 5w40 specifically states "Specialist product for VW PD engines requiring the 505 01 specification"