At the moment I have a 5W30 (or 10W30) in my Toyota Aygo. However, very little of it. There was nothing left to see on the trackstick. I would like to drop some oil. At home I bought a good 15W40 (actually for the beetle, still new and unopened). My question is – can I refill with 15W40? Or should I just change it completely? What’s a bit surprising – the oil was last changed in September 2018 and I ride about 1200 km a month. otos: one from the instructions for use of the car and one from the oil. In the instructions for use it is clear that 15W40 with API SL is in order. On my oil is also API SL. The question is whether mixing is possible?