Most of this doesn't relate to OP's original question and car at 40K miles. Short answer, do it (the synthetic).

 

synthetic.

 

So would you guys suggest going with 5w-30 for summer, and then switching to 0w-30/20 for winter?

Which would you guys prefer for winter? 0w20, or 0w-30?

I think it would be a good idea to switch over to something better for winter cause it gets pretty cold here in Canada during winters lol

 

........

 

Synthetic. I'm using Mobil 1.

 

This. Mobil1 Fully Synthetic 10W-30 is what I run. It runs me about $55 for an oil change with synthetic (compared to $39 for non-synthetic). I generally do oil changes around 7500 miles.

 

I would stick with just 0, which was done for my car and all of the other family member's cars. 0W-30 for the cars before 2011 and 0W-20 for the 2011 cars - even thou you could put this oil in the older cars.