Your Holden/Opel Astra requires an ACEA A5 oil, check the bottle for that spec in a 5w30 weight oil. Synthetic oil can either be 0w30 or 5w-30.
Yamalube motor oil
The recommended oil is SAE 5W-20
10W-30 motor oil is recommended for the 2005 BMW X5 automobile. When the automobile is being used in extremely hot climates 10 W 40 motor oil is recommended.
We have a 2005 Astra AH model with the Opel motor, apparently Repco do not stock the required Oil, it's a fully synthetic oil that is very light. Holden have it at $30 per/L and is Red in colour. I have been told by a number of people now not to mix these oils and to use the recommended oil for the car, so I am about to take a trip myself to holden.
For 1.6 liter Vauxhall Astra cars the recommended oil choice is 10w 30. For higher mileage engines synthetic blends are also a good choice to help keep the engine clean.
For cars, the manufacturer recommended motor oil.
5w20
10W-30 motor oil is recommended for a Montero sport, under normal conditions. When the vehicle is used in a very hot climate 10 W 40 motor oil is recommended.
The recommended type of motor oil for a 2007 Cadillac Escalade is 0w-30 Signature oil.
It is recommended to use 10 W 40 motor oil in a 2003 Chevrolet Tahoe engine. It is also recommended using 10W-30 motor oil in a very cold climate.
5w30 is recommended about 3.5- 4 quarts is normal
10w30