Pennine oil - quality rating?

[Oldmogman]

Does anyone know the rating for Pennine Heritage Classic 20W/50?

I want to see if it's comparable to the oil I'm using at the moment, which is marked: 'SL/CH-4' and '1300 zinc as ZDDP'.

I did email Pennine's customer service department but didn't get the courtesy of a response - not a good way to win customers!