Originally Posted by NJUPINTHEAIR

FYI:

I just used my "old" MR visa at an unattended tix machine at a tube stop in London to refill my Oyster card and it accepted the card even though I don't think it has the new chip technology -- the card is certainly no different in looks from the old card.

As this is a heavily touristed Tube Stop -- Green Park -- it could be that no such chip filter technology was required here perhaps because of the number of Americans that use this stop.