Your grange might do all sorts of things and it may be hard to generalise. I'd decant it and then taste it regularly until it seems ok and then pour it back into your cleaned bottle and then seal it until you're ready to drink it. Then it should be fine -if it is ok..The RWT is not old - it is very young and may need a few hours of decanting time or more - do the same with this one starting maybe 6 or 7 hours before service.
If you can remember what a wine is like the next day you didn't drink enough of it Peynaud
For a 36 year old wine, I would suggest not very long at all.
I am being advised by wine merchants and sommeliers in France to not decant their 20+ year old wines at all. Instead,they recommend pouring into the glasses they will be consumed from, 15 minutes before service. I have bucked this trend and decanted for 30 minutes and not lost a wine, but can understand why I am receiving this advice.
For a more robust wine like a Grange, a decant of no more than 30-45 minutes is my call. For the younger RWT, start with 3 hours and taste it.
Wine, women and song. Ideally, you can experience all three at once.
What is the definition of OLD Wine? How old or how many years? Tea strainer is quite good like Dave mentioned. I try tea strainer for 1993 Seppelt Drumborg Cabernet Sauvignon. I broke the Cork when I opened it. I couldn't get it all out. I have to use tea strainer as filter. Pour into glass and leave it for 1 hr. The outcome was impressive. But for Grange, maybe not a good idea.
I've used my stainless steel fine meshed tea strainer for crumbled cork. It also catches the larger bits of sediment. The finer sediment I try to leave in the glass and rinse it.
Aged notes is not for everyone, most people I know prefer young-medium aged, while I like them reds bit aged. I know couple guys cellar Wines and when time came, they didn't like it, often pays to sample some aged wines from merchants or auctions before you start up cellar.