Calls for 5W20 but want to use a synth and squeeze every last drop of fuel mileage out of it. I'm starting to become a believer in the whole "thin oil thing" but am still a little itchy about running it in mid July. It's the missus car, so it's driven in a civil manner and is used on a 80 mile mostly xway commute so the recommended 7500 OCI seems long enough. Just anxious about high temp protection. Thoughts/opinions/rants welcomed and encouraged. Thanks.