Esso Ultron Wanted or Mixing Oil Question

[tjdixon911]

I am after some 5/40 Esso Ultron Oil to top up my car but can't seem to find any locally anywhere, does anyone know a stockist that may do it mail order?

If not what are the rules on mixing oils? what is compatable?

The cars a Porsche 968.

Any help much appreciated.

[GavinPearson]

I woul use a good synthetic oil of the same grade such as Mobil 1. As both are products of ExxonMobil they are probably very similar.