1995 c200 Petrol Grade
 

Hey guys, ive got a bit of an unusual one here.

In new zealand we have 91 and 96 grade fuels same as in australia. Premium is 96 obviously - so this is what Ive been running in my car.

However with the price of petrol going up, I tried regular 91.

With 96, the car smells like rotten eggs when driven a bit harder than ussual, and stumbles slightly when cold (nothing that would cause concern).

However with 91 the car doesnt ping, it has more power and is more responsive and it doesnt smell of rotten eggs.

Why? These cars are meant to run on 96.

i believe the owner's manual is asking for 91 grade only, at least for north american models. is the grading system different in new zealand?

yes i believe the grading system is differnet....theres RON and MON not sure which it is but its diff

RON = Research Octane Number
MON = Motor Octane Number.
In North America we use RON + MON : 2.
I.e. 90 + 96 = 186 : 2 = 93. ;)

Ok, we use RON in new zealand, the two grades are shown below. Ive been using 95RON (its sold as 96 at the pumps which i find quite a gimmick). However it seems to go better on 91 RON.

(91 RON/82 MON) and premium (95 RON/85 MON)