Last month I changed my oil in my old F150 w/ I-6. It was pretty hot out then and I put in Maxlife 10-40 and added a pint of Sheaffers moly EP. I only have a couple hundred miles on it now but will run it this winter. I usually put 5-30 in it for the winter months. Now the temp is down into the 20's and 30's in the mornings and maybe reaching 40-50 during the day. So, my question is will the thick HM 10-40 with the EP in it be too thick when it gets even colder, say 0-30 degrees F? Should I change it out soon or not worry about the hearty, bulletproof I-6? Just let it warm up longer? I won't reach my normal OCI of 5,000m until about January or so. Discuss...