Does anyone know how to change the gearbox oil in Vectra B 2.6? it has an Aisin 50-40LN AF22 gearbox. How to drain it, at what temperature, how much goes in after draining? Some information suggest that you can't get all 7 litres out and refill is only about 3 litres. Currently at 20 degrees C the oil level stick is way up to the top, it seems there is far too much oil in it.