Nitroplait
Well-known
Shot some expired HP5+ in Rodinal and I know its not the ideal dev for HP5+ but its what I've got and its what I like for everything else, but seems really grainy negs look a bit thin too.
How long past expiration date?
Kept in room temperature (20-25°C) I see only minor degradation in HP5+ and TX400 over a period of up to 8 years past expiration (which is the oldest expired film I have knowingly used).
I use HC110 which is better for expired film than most developers, but HP5+ should be able to produce acceptable results many years past expiration with small adjustment in exposure and development.
If you have a large stock of expired film, I'd advise you to buy some HC110. It is as easy to use as Rodinal.