How many miles you at now? I usu. wait till 10K miles to switch to synthetic personally. I guess depending on how close you live to the Arctic Circle( it seems like half the Canadians on here live in Yellowknife where its cold AF) probably Redline 0W20,5W20 or 0W30. I run 5W30 year round but it never gets below 20* here, hell its 63* right now. I'm currently running Quaker State Ultimate Durability 5W30 in my truck and its been great for 1K miles so far. On the other hand I put the same oil in a used challenger I bought 3 weeks ago and it didn't have quite the impact I was hoping for. I have 7 qts of Redline 5W30 sitting on the workbench in the garage waiting to go in the Challenger as soon as I can get around to it. I know for a fact that it will make it quiet.
