So I've been doing a lot of research into oils and want the best going into my engines weather new or old. But theoretical situation.
Mobil 1 HM or Valvoline HM
Motul 8100 series oil (Has Esters, it's in the FAQ on the Motul site)
So I was reading about Ester based oils and they have property I found interesting, they actually cause seals to swell, not sure what they do to offset this to prevent damage to seals. So would Ester oils be more affective in stopping leaks do to seal shrinkage or minor damage than seal conditioners in High Mileage oil?