We had family visit from the states and of course we have driven all over England. I have some time today to do an oil change. The issue is its 30 degrees out and I'll have to do it in the coldish weather. The oil currently in the engine is 5W30. Should I warm it up a bit to get it up to temp, or just open the oil plug and let it drain cold? Thinking it would be more on the 5 weight side if cold, and better flow. I'm also thinking of doing a transmission fluid change as well. Ideas?