Might be better to ask Ford if any oil that meets their spec for that engine may harm the wet belt. Could be all kinds of oils on the market may degrade the rubber belt over time that meet the Ford spec ... or not. Only time will tell, unless Ford can tell you with confidence that they've engineered and tested it to not be a concern or not a concern if certain oils are used. Does the OM have a big warning about what oils to use with the engines with the wet belt?I did email Valvoline and received a somewhat expected response along the lines of “…it means Ford’s WSS-M2C961-A1 spec and therefore is safe for use.” This was specifically regarding Ford’s change to the oil pump driven belt in the F150 5.0 (which I own). I know 2.7’s have been using them for a while now but VRP is just now coming on the scene.
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