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.
My GT is coming up on 1000 miles. I will do my own oil change around that time. I plan on using either Pennzoil Ultra Platinum full synthetic or some kind of Mobil 1 synthetic. Probably the Pennzoil since that's I've used for years with no problems in both my personal vehicles and several of the vehicles my company owns.
Of course my dealer wants to use Motorcraft Semi-Synthetic I think because it's cheap.
Any constructive comments on the Pennzoil Ultra Platinum, which is my preference, and going straight to full synthetic from the factory fill of semi-synthetic would be appreciated. Yes, I know, I know, I did a search. This is 2025 though.
@Abilor ..... very interesting, brings back memories. We used to use through the dipstick oil tube extractors for our marine engines. We knew we weren't getting it all as that is simply not possible with that system. Used it for thousands of oil changes. As we built more and more expensive marine engines we had to make sure we were extracting as much oil as possible - aiming for 99.99% After using our typical dip stick tube oil extractor we removed the plug from the oil pan. The tech started yelling for some rags as oil was draining into the boat's bilge. Note - the bilges on racing boats are pristine and owners get really pi$$ed if there are dirty oil stains in them. Now what, we wondered? We found brass 90 degree angled tubes that we could screw into the drain pan plug holes. Note - when we "dry fitted" the brass piece we noticed it stuck above the bottom of the oil pan depression by about 1/4 inch so we cross cut the brass fitting to allow maximum drainage. We attached custom fabricated stainless steel braided hoses to the brass fittings and ran them up into the engine bay and topped them off with an on/off valve. They were then affixed to a stainless steel mount. To change the oil, which was done after every race or even a hard weekend of play, we used a custom electric vacuum pump. Doing this we got all (99.99%) of the oil out of the pan. The oil filters were on remote mounts on the top of the engine. A friend who saw what we did modified all of his shop trucks (he had 25 or so) with this system and it saved his mechanic a $hit load of time and therefore money. I am sure using your through the dip stick tube is good enough for what we forum members do as we don't have to get all the oil out ..... so I write the above just for amusement.
