I was wondering if anyone can give me a definitive answer about the kind of oil to use. I live in Chicago and it just snowed today, when it gets cold out my car starts fine but you can tell its running really rough (car vibrating and such). I run the car about 60 miles a day and it just seems like it never really warms up to smooth riding the entire time. I had 10w-30 full synthetic in there in the summer and just got an oil change today. I was going to put in 5w-30 full synthetic like I did last winter but after they drained my oil they told me they were out of it. They put 5w-40 in there for me.

How is this in comparison to 5w-30? I know that 5w flows better than 10w when its cold out and 40 flows less than 30 when warm but I think I am looking for a less visocisity all around since it's cold out--or will this not matter? It has 144k on it and i felt like the cold driving w/ 10w-30 was killing it..but theorhetically higher temperatures with 5w-40 would actually provide less flow less the 10w-30. I need some good advice on how the cold driving will be affected by the 5w-40. I have no problem changing the oil out to 5w-30 if anyone here is certain that it will provide for a smoother ride all around and that the 5w-40 will somehow adversely affect driving.

Also, I just noticed that some companies offer 0W oils. Would a 0W-30or40 be even better?

Any help is greatly appreciated.