Thanks everyone. I flood my bottles with nitrogen so I'm sure I can get your recommendations to last.
If you use plastic bottles the oxygen from the air can diffuse slowly THROUGH the walls and caps of a plastic bottle. So flooding with nitrogen helps but you really need to use glass bottles if you want really long life. I have stored both Xtol and D72 and D76 in small glass bottles (330ml) for an age test and even 4 years later they are colorless and work as good as new.
Yes, IIRC about 1:20 dilution of Rodinal - but it's been years since I've done it. I think there's a thread on APUG about it. I don't remember what papers I used to try it. Probably Canadian Azo and Kentmere Bromide. The result was a somewhat cold toned print. I didn't continue because it was not very economical. I think there's also a thread about using Gainer's PC-TEA as a paper developer.