Opel Corsa B 1993–2000 Service and Repair Manual: Unleaded petrol - general information and usage

Note: The information given in this Chapter is correct at the time of writing and applies only to petrols currently available in the UK. If updated information is thought to be required check with a Vauxhall dealer. If travelling abroad consult one of the motoring organisations (or a similar authority) for advice on the petrols available and their suitability for your vehicle.

1. The fuel recommended by Vauxhall is given in the Specifications Section of this Chapter, followed by the equivalent petrol currently on sale in the UK.

2. RON and MON are different testing standards; RON stands for Research Octane Number (also written as RM), while MON stands for Motor Octane Number. Fuel requirements are as follows.

1.4 and 1.6 litre models

3. All 1.4 and 1.6 litre fuel-injected models are fitted with catalytic converters and must therefore be run on 95 (RON) unleaded fuel only. Under no circumstances should leaded (UK "4-star") fuel be used as this will damage the catalytic converter.

1.8 litre models

4. All 1.8 litre models are designed to run on 98 (RON) octane leaded or unleaded petrol. If it is wished to run the vehicle on 95 (RON) unleaded petrol the following operations must first be carried out; this is necessary to avoid detenation (knocking and pinking) which could lead to possible engine damage

5. On early (18E engine) models, to allow the vehicle to run on 95 (RON) unleaded petrol, the ignition timing must be retarded by 3º. Do not use 95 (RON) unleaded petrol if the ignition timing has not been retarded.

6. On later (18SE engine) models a fuel octane rating coding plug in the ignition system wiring harness (see illustration). The plug which is located on the right-hand side of the engine compartment, is set during production to give optimum engine output and efficiency when run on 98 (RON) fuel. To run the vehicle on 95 (RON) unleaded fuel, the plug position can be reset to modify the timing characteristics of the ignition system. To reset the plug, release its locking clip then remove the plug and rotate it through half a turn (180º) before reconnecting it.

Note: If after making the adjustment, the octane rating of the fuel used is found to be so low that excessive knocking still occurs, seek the advice of your Vauxhall dealer.

Octane rating plug in the "95" setting position

2.0 litre models

7. On all models with a catalytic converter, 95 (RON) unleaded fuel must be used. Under no circumstances should leaded (UK "4-star") fuel be used as this will damage the catalytic converter.

8. All models not equipped with a catalytic converter can be are designed to run on 98 (RON) octane leaded or unleaded petrol (see Specifications). If it is wished to run the vehicle on 95 (RON) unleaded petrol, the fuel octane rating plug must be set to the "95" position (see paragraph 6); this is necessary to avoid detenation (knocking and pinking) which could lead to possible engine damage