I have two questions one specific to my current situation and one generic 1) Specific - I changed oil Early June 2018 . M1 5W20 with M1 110 filter . Since then and now I have got 8000kms on the clock In mid Aug 2018, I found a leak in the oil filter so my filter was changed. Stupid pit top student poured a full 1 liter bottle whereas an oil filter only contains 300ml or so oil. So I had to take out 300ml oil out else it was an overfill.. Then as my car burns oil, I add another 500ml in somewhere Dec 2018.. Then my car stayed outside Mechanic's garage for full 2 months in -30 to -40 deg C while I waited for parts. In these 2 months the car was started 2 to 3 times to move it from one side of garage to other side. Finally car was fixed in Feb 2019 and I added another 500ml in March to bring to full mark on dipstick. car sitting outside for 2 months in those crazy winter months and also being started a few times might have made my oil acidic, moisture full and oxidized? I took it to highway for a 100kms to burn moisture etc but thought of asking. should I change oil now? 2) I was thinking to switch to M1 EP 0W20 and do yearly OCI. In winters , I do have to do some short trips but every couple of weeks do take the car to highway 50 to 100 kms.. Is yearly OCI fine or I should stick to 6 months here in Winnipeg. or perhaps go 9 months?