V50 2.5L Turbo – which oil?

Hello, I’ve just got a bit stunned because I looked at my oil stand in the car – the rest was not too much to complain about. But: In the engine compartment is a Volvo sticker, that you should fill an oil with 0W30. For fun I looked at the note, which my friend put in the engine compartment, it was used with the last change through the Volvo workshop a 5W40 oil. and now? What is the difference – drive on LPG but it also means you should always use the oil, which the manufacturer pretends… Pope