AZ_Ryan
Well-Known Member
The S550s had an access panel as well.The concern is that some synthetic oils in the US are not primarily synthetic. They are group 3 base which is derived from mineral oils but are highly refined. Mobil filed suet against Castrol for this in the 90s because Castrol labeled their Syntec oil as being 'synthetic' but was derived 100% from mineral oils. Somehow Castrol won and many companies changed their synthetic oil bases to be derived from mineral oils (or natural gas like Mobil) to save cost/increase profit. Group 4 base oils are polyalphaolefin (PAO) synthetic base oils. Additives can be other group oils. I do not know if there are any full group 4 oils out there but Euro spec oils are the highest % group 4.
Now all of this said, without testing, you do not really know how the oil is performing for your use. Group 4 base oils will out perform Group 3 base oils but you may never wear out a Group 3 base oil depending on how you drive or how often you change the oil.
Ford recommends their semi syn oil for this engine and oil change interval (10k miles or 1 year) so any synthetic oil that meets or exceeds the same standards is going to be good. I use the full syn motorcraft in the mustang. All of my other vehicles get Castrol, Pennzoil, or Valvoline (VW Euro spec).
Also, the number of fasteners to remove in order to do an oil change is painful on the mustang. My 2012 Xterra had an access panel on the skid plate to get the filter. Granted that was in metal vs plastic. Maybe that would be a worthwhile product to bring to market to reduce the labor for oil changes. As the plastics age, they will lose shape and be more of a pain to realign.
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