I have a 2005 Dodge Grand Caravan (3.8 V6). I am currently using Havoline 5W/20 (manufacturer's specified weight). I put 15-20000 miles per year on my vehicle. My habits are this: short trips 1-2 miles (very often) to long trips 100-600 miles occasionally. During the summer and fall, I pull a pop-up camper to Arkansas and Colorado. I live in South Dakota which has very cold temps. I do a 5000 mile OCI (every 3-4 months). Based on my driving habits, would there be any benefit to using a synthetic blend (Motorcraft 5W/20) over my regular Havoline 5W/20?