Ive never had a single problem with either Ultimate or Optimax
I actually put Optimax in last nite after running Ultimate for the last 6 months, My car starts better and idles better with Optimax but other than that, they both react exactly the same at 12psi@7000rpm
Optimax does smell a little more but thats cos it does have some kind of cleanser in it, although it would be very weak, its definatly there.
Id would be great if one of them brought out a 100 octane pump fuel, BP is already making a killing off Ultimate. Im hoping Mobil do it, cos Mobil currently doesnt have synergy 8000 in QLD yet. Although there is hardly any mobil servos around anyway.
At the end of the day they are both 98 octane, and aslong as you dont get a bad batch, they should react pretty much the same. If anything youd think Shell would be better, considering Shell is the most profitable oil corporation.
meh