Just a quick question, I have an 09 Dodge Ram 1500 with the 5.7 mds motor. I was going to run Mobil 1 syn 5W 30 in the summer and the Mobil 1 syn 5W 20 in the winter, the manual states to use 5W 20. Would it be ok to run the heavier oil or should I not even bother and just stick with the 5W 20, my driving style is a 50/50 mix of city and highway driving with sustained speeds of 80 mph for about 1/2 hour or slightly more. The temperature outside has been in the lower 90's. Thanks in advance, Sal