Hey guys, long time no post. Got a question I'm sure you will be able to help me with, I'm changing the oil in my girlfriends car tomorrow. It is currently running 10w40 blend from the last garage service. I have laying around odd quantities of Valvoline Durablend 10w40, Mobil 1 0w40, and something called Quantum Platinum 5w40 synthetic, which is the oil VAG dealers here use and is made by Castrol for VW. Is there any danger in mixing the three you think? Bearing in mind that one is syn-blend, one is 'synthetic' and one is actual Mobil 1?