Originally Posted By: StevieC
Doug Hilliary has answered that question numerous times. Just because the numbers are high doesn't mean excess wear or premature failure.
I suggest you PM him for the story before this turns into another M1 bashing thread.
Doug has torn down numerous engines with long OCI's using nothing but M1 and has shown the engines to be in perfect tolerances, including cylinder walls where the Iron is supposedly coming from.
M1 5W30 has significantly higher camshaft wear measurements in SQIV tests than similar QS, Valvoline and Castrol full synthetic products.
By coincidence M1 5W30 also typically has higher than normal iron numbers in UOA's posted here.
But many members here back M1 and dismiss the UOA results because they can't be proven to correlate with wear. Others argue that engines don't need to last 1,000,000 miles and M1 wear is acceptable.
Doug has a lot of experience but long distance highway diesel trucks in austrialia don't have a lot in common with the average stop and go gasoline engine in NA.
M1 has some fine oils but why would I pay top dollar for an oil that provides adequate performance. Now if i could get M1 on sale and apply the $10 rebate folks in the USA can get I would buy some M1 0W40 tomorrow.