Originally Posted By: zddp77
Time and time again high Iron with Mobil 1 , this is a 15,000 mile oil run only 4,200 miles with poor results. Switch too any other brand name synthetic and you will get better results.
Skip the synthetic completely, and switch to a good quality dino. Change it in April and October (to avoid that middle of the winter change). Your mileage seems to be about 5k every six months so this should work out perfect. If you take a road trip, one extra change a year won't kill you.
Check out this
UOA on the same engine with Pennzoil YB. Great results on more miles than the Mobil. I am not sure that the Mobil is responsible for the sodium, but you need to try something else to be sure IMO. Who knows, maybe XOM had another formula change and went back to sodium as a cleaner. To my knowledge, Valvoline still uses it in MaxLife, so it may just be an additive.
Unless you plan to run a yearly OCI, you are wasting money on synthetic in this application. Plus I'm not sure a yearly OCI would be a good idea with the winters you get in Michigan.