I never saw anything wrong with the motorcraft oil. in fact I prefer it
when I bought my 87 ranger it had over 200,000 miles on it, I always ran motorcraft 15w40 and a can of 4 cylinder restore, and the truck still ran like a champ and passed inspection, and did not smoke the day I sold it with over 300,000 on the original motor.
I would not recommend putting 15w40 in a motor as new as yours though.
also I would not recommend any synthetic oil ever.
I bought a 2000 ranger 4.0 brand new back in the day, and on the first oil change I put full synthetic pennzoil 5w30, and it had a slight tap that never went away ever since. it didn't have it before but always had it after no matter what oil I ran even when I tried putting in synthetic blend, and even regular motorcraft 5w30.
I can't say I had any excessive engine wear or anything, I just was pissed off about the tap... not to mention after experimenting with different oils over the years, I don't see anything wrong with regular oil, especially if you are changing it every 3000 miles.
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