Originally Posted By: earlyre
you don't even wanna guess how many hundreds of thousands of miles my dad put on (at least 5)Aerostars w/ that engine(built here!) running 10w30, year round, in Ohio, Indiana, and Michigan. you will be fine.
remember that engine was designed for a 30wt(prob.10w30) then ford back spec'd nearly everything to 5w20.
As i have researched this car to a degree, i can agree that it was not speced for 5W20 til 2001, and 1986-2000 it was speced for 5W30. Since the OP is in the deep south 10W30 will be perfect for that climate. Ford used to put a chart in its owners manuals for oil, saying that 5W30 was for below 0F to the above 100F range, and 10W30 was for 0F+
Use 5W30 like i did, and will again, and a FL400s and the vulcan will be perfectly happy, mobil 1 in this engine is not worth it, PYB of QSUD will be perfectly happy in it, 5,000 mi oil changes as well. These engines are not very picky about oil, only thing that they are picky about are coolant flushes, and spark plugs.
Coolant is every 2 years on these engines as they contanamate it rather easily, and spark plugs are double platnium due to the wasted spark ignition system, Champion and Bosch are two to stay away from on ford engines, cause coil pack issues.