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 shown in the Specifications, 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 .

3. 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.

1.2 litre models

4. On 1.2 litre models produced prior to February 1985, unleaded fuel can be used in these models but note that to every five tankfuls of unleaded fuel used, one tankful of leaded fuel must also be used.

5. On later 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.

1.3 litre models

6. On models with 13N and 13NB engines, 95 (RON) unleaded fuel can be used without any modifications.

7. On models with a 13SC engine, 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.

1.4 litre models

8. All models can be run on 95 (RON) unleaded fuel can be used without modification.

1.6 litre models

9. On models with a 16SH engine, 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.

10. Later models with a 16SV engine have 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, make sure the plug is set to the "95" position (95 should be visible on the side of the plug).

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 plug in the "95" position - later 1.6 litre models