Suitable petrol octane rating

[fred]

According to the owner's manual, I can use a minimum 87 octane petrol if the car has no catalytic converter, minimum 95 octane if it does. Anyone know if my car came equipped with a cat converter? It's a 1990 230CE

 

[Karl]

There was no cat on the 1990 230 8 valve engines. Uk unleaded is 95 octane anyway so no probs either way. If you want a bit more go, use Tesco 99 unleaded but to make the very best use of it you will need to advance the static ignition timing a few degrees.
IE. turn the ditributor in the opposite direction to the direction of the rotor arm.
Mine is a 1990 230E with 12 degrees of advance to make full use of 110 octane LPG.

 

[GrahamC230K]

I assume Fred is not in the UK.

 

[fred]

I'm in Singapore. We have 92, 95 and 98 at the pumps.

 

[grober]

My first 2.0 LITRE 190E(SIMILAR ENGINE) had had its ignition retarded to run on unleaded fuel when I bought it. This lead to it running hot and possibly the premature expiry of the cylinder head gasket at 30k miles. I ran it on 98 octane after that and it was still going strong 90k miles later when I sold it. I would be wary of running anything less than 95 octane even if you can. Poor octane fuel=shorter engine life IMHO You can retard the ignition but to make the engine completely compatible with lower octane fuel you would have to lower the compression ratio. In both cases you will lose power and fuel efficiency so gains would be marginal