Took my AW11 for some semi-hard driving around the Waitaks today, noticed on the way back that it felt a little harsh. Stopped at a petrol station and checked oil - low, so topped up with a semi-synthetic 10-W40 I believe it was. Im not sure what it was running on before this, as just bought it recently, will check with the previous owner soon. What would be the ideal oil for a bluetop 16v 4AGE?