Engine oil, what type?

[wouldhee]

What oil should I use in my 1938 P2?
What do people use?
where is the best place to buy?
Are there "things!" in modern oils that make them unsuitable if so what would happen if it was used?
Paul

[Phil - Nottingham]

Certainly not lightweight semi-synthetic modern oils - a good 20/50 is considered the best eg Castrol Classic although I have used Comma Premium 20/50 for years in my P2 and P4.

Its not the miles between oil changes although I would change every 1500 max but time span - 18 months max is what counts

[47p2]

I use Penrite Classic HPR 30 which is a 20w60 oil