Hello everyone, I hope you are all doing well on these hard days. I have an audi a5 1.8 turbo gasoline (2010) tfsi 118kw, and have an a bit increasing oil consumption problem since some time. It all started since a year but I probably noticed the increase abit later. I suspected from the authenticity of the oil that I added on top of the oil inside and immediately switched to different brand from different seller (a month ago). And the car was driven with the suspicious added oil (about 2 liters in 2000km) for 2 months. The rest of the oil inside engine was 4 months old (max 5000kms). But although the oil inside the engine was from a different seller, I started to suspect from that one as well later on. But before that oil change there was also a bit increasing oil consumption, however I can not remember the details as I mostly kept the car in garage last summer when I travelled around. I hope that the oil did not damage the engine as I started to have suspects about it.But its too long ago and I already replaced the oil filter (from the dealership) and oil (different brand from the distributor). It is now 2000 km since last oil change (1 month ago) and I already added totally 1.5 liters of oil in smaller amounts at different times. In the past it was 1/5 liters in around 6000 7000 kms. Last month I also replaced the PCV valve with the genuine one (old version ending with AH) as a preventative maintenance. And there is no change at oil consumption. The car always had 5w30 oil since new. And since 3 years of my ownership I always used mobil 5w30 c3 esp (I change oil at every 7000-9000km). Last month,I switched to Liqui Moly 4200 5w30 at last oil change. To reduce the consumption I am thinking now to switch to Mobil 1 0w40 or Liqui Moly 5w40 oil. And got confused as I dont know whether it is better to choose a3b4 version or c3 version of those brands (both have vw502 approval). The car manual recommends vw504 for longlife and vw502 for control service. And it says that I should not add more than a liter of a3b4 oil. In this case can I use any Vw502 (whether a3b4 or c3) ? Or should I use Vw502 c3 only? I see people with tfsi engines using mobil 1 0w40 but they never mention whether it is the New Life (a3b4) or ESP (c3). Which one do you recommend to reduce oil consumption as much as possible? Can I really use vw502 where vw504 is recommended ? Arent those two approvals designed for different engines? Look forward to get answers to my questions. Many thanks in advance.