The two most popular Astra and Vectra models, as well as the Kadett for an additional year, were equipped with the 1.8-liter Opel C18NZ engine, which was assembled at a German company between 1988 and 1995. The device is a scaled-down version of the C20NE and has nothing to do with the C14NZ or C16NZ motors.

The C14NZ and C16NZ engines are also part of the C10 line.
The engine was mounted on:
- Opel Astra F (T92) in 1991 – 1994;
- Opel Kadett E (T85) in 1990 – 1991;
- Opel Vectra A (J89) in 1988 – 1995.
Specifications
| Production years | 1988-1995 |
| Displacement, cc | 1796 |
| Fuel system | single injection |
| Power output, hp | 90 |
| Torque output, Nm | 145 |
| Cylinder block | cast iron R4 |
| Block head | aluminum 8v |
| Cylinder bore, mm | 84.8 |
| Piston stroke, mm | 79.5 |
| Compression ratio | 9.2 |
| Features | no |
| Hydraulic lifters | yes |
| Timing drive | belt |
| Phase regulator | no |
| Turbocharging | no |
| Recommended engine oil | 5W-30 |
| Engine oil capacity, liter | 4.0 |
| Fuel type | petrol |
| Euro standards | EURO 1 |
| Fuel consumption, L/100 km (for Opel Vectra 1994) — city — highway — combined |
10.2 5.5 7.6 |
| Engine lifespan, km | ~330 000 |
| Weight, kg | 130 |
Disadvantages of the C18NZ engine
This engine has no obvious flaws; all of its issues are caused by aging;
Most frequently, the ignition system malfunctions or certain sensors are defective;
Hydraulic lifters will knock closer to 100,000 kilometers if you use low-quality oil. The timing belt has a small resource, but when it breaks, the valves do not bend.
