Hi fellas, I don't see an "introductions" subforum here, so I will let this be my introduction. I have poked my head in on this forum a handful of times over the last few years but nothing really consistently. recently i have done a bit more reading on here and found some info that makes me question a few "ideas" i had about oil/filters/changes. I live in Canada, Regina Saskatchewan to be specific. My wife and i own 2 cars, a 2008 acura TL (3.2 v6 auto) and a 2010 Mazda 3 (2.5 i4 auto) both of which I do the maintenance on. Both cars have ~120,000km/ 75,000mi. The I drive the TL around 1200km/month, 80% city driving, the mazda gets maybe half of that, also mostly city driving. Neither vehicle is driven spiritedly on a regular basis, the Acura on occasion only. Up till now i have changed oil 2x per year, fall and spring with castrol edge synthetic (I am considering changing to a different oil as this one seems to be on sale less frequently, and others do have better sale prices that i have seen locally, but this is besides the point). I have not really kept track or done the math until now, because i knew i was under the recommended OCI for synthetic, but that means ~7200km/4500mi OCI for the Acura and again half of that for the Mazda. I have always been aware that synthetic oils can safely be used for longer OCIs in the typical DD case, and after reading on this forum and doing the math above, i realize i am potentially using a lot more oil than i need to, especially with the Mazda. I am considering stretching out my OCI's, potentially for a full year but i do have some reservation with doing that. The main thing holding me back is our climate. I see others on here have done 12-18 month OCI's, but i haven't noted the climate/location driven. Here in SK we have temperatures in the 30C/86Fduring the summer, but also have portions of winter when the temperature doesn't get warmer than -20C/-4F for a week straight, dipping down to -40 at times. It is the winter that worries me, and is part of the reason i have changed my oil 2x per year recently. I am not confidant my commute to work gets the car warm enough to boil out condensation/fuel in the oil (12km/7mi, all city). Am i safe to run the entire year on the same oil, through such winters, or is it better to play it safe when it comes to the potential of water/fuel in the oil? Part 2: if it is reasonably safe to run 1 year OCIs, would you prefer fresh oil heading into the winter season, or heading into summer? please forgive the noob questions, and if this question has already been asked/answered please point me to the thread/s. i did do a search but came up empty. thanks in advance for the help.