Best oil for 2.4D DW?

[blix99]

Hi there. I have a 1983 2.4D DW in a VW LT camper van, in the UK.
I've read a few posts; here and on other forums, about which oil to use but nothing seems conclusive.

Mineral? Semi Synthetic? Fully synthetic? What grade?
I found an LT owners manual in German that seems to suggest 15w40 mineral but this was from the late 1980s so think things might have moved on from here. It also specifies VAG 501 01 but since this forum is predominately Volvo and uses the same engine, I can't see the VAG spec oil makes much difference?

From what I've read, mineral oil deteriorates quicker and leaves more mess whereas Synthetic, either semi or fully, cleans the internals?

Any advice for the best option to keep my engine running tip top would be greatly received : )

Cheers