I don't know, but I know that the guys at the Auto Parts store initially sold me Mercon III for my 97, which was incorrect for at least the 97, but apparently was correct for prior years. That's what lead to my baptism into the world of gentle flushing. <sigh>

 

For my '97, the owner's manual tells you to check the tranny dipstick for the fluid spec. Seemed odd. Mine said "Mercon V". Surely Ford didn't use different fluid types in different trannies of the same model year?

 

inmI looked through 370 pages of my 1996 Aerostar's owners manual. It says to look at the dipstick, also. The dipstick says to use "Mercon". No suffix. I have changed the fluid a few times, and have paid to have it done. When I change the fluid I use Valvoline Dextron III/ Mercon fluid. The van (and Tranny) have about 142,000 miles on it. (228,000 KM for you metric friends out there) I have a ski boat and do lots of towing on short trips from mid March through October, and do a few longer trips during the Summer. I live on a hill, about 550 feet above sea level, and the river I frequent is about 50 feet above sea level, the round trip is about 8 miles. I probably do 50 or 70 trips to the river each year. No tranny problems so far. Knock on wood. I have an owners manual for a 1966 Ford pickup, and has Ford Spec. M2C33D for the automatic in this truck. (Cruise-0-Matic) My 1974 Ford pickup, with a C-6, has this spec number on the dipstick. By the way, I also use this same fluid in the power steering of my Aerostar van, the power steering of the 1974 pickup, and the power steering of the 1966 pickup, if the 66 had power steering. I also use theis same fluid in the transmission of my boat, but that belongs on the Planetnautique forum. So, for 40 years of Ford vehicles I am familar with, the same fluid.

 

the '96 and prior model year Aero trannys A4LD's and 4R44 4R55 4 speeds all spec Mercon (aka on shelf as DextronIII/Mercon) which has less Friction Modifiers in it aka FMs

starting in end of '96 and '97 Aeros the 5R55E 5 speed auto tranny was used....these spec Mercon V aka Mercon5 which has higher levels of FM due to a change in the friction materials and design pressures used in the clutch packs and bands....

read the tranny dip stick in the vehicle and the owner's manual if still with the rig....'96 was a split year....dipstick spec is not cast in gold guarentee of ATF type, may have been changed....check year of veh and VIN tranny designator and door plate number for tranny id #

using MerconV 5 in a tranny rated for regular Mercon can cause band and/or clutch slippage, excessive wear and overheating.....using straight old spec Mercon in a newer tranny spec'd for MerconV 5 can cause agressive rough grabbing shifts....

best to use the correct rated ATF...situation is going to get crazier for Ford model ATFs....two new ATF specs are out for the newest super duty PU's and more ATF specs are on the way for the new diesel cars and lt pu's coming...we will soon be up to 7 or 8 ATF's to cover just Ford's.....Ford spec F ATF will soon be dropped by most major manuf.'s and become a specialty fluid for racing and the older Cruisomatic C6's
do NOT use type F or FA in an Aero tranny...sudden DEATH
M2C33D is one of the earlier specs for Ford type F ATF

Lubeguard and Smart Blend make ATF additives to Friction Modify an ATF to match the application...also adds cleaning and heat protection esters to ATF....avail. at most auto tranny shops and parts retailers....i use to the Platinum to modify the friction level of the ATF's used in my rigs for shift response and heat breakdown protection

type F or FA is spec'd for many power steering systems in Fords....check your book or pump cap....many use Mercon also....Mercon will quiet down some noisy pumps with the extra FM helping the pump components slide easier and quieter

Valvoline Maxlife ATF also works well in worn noisy seal leaking power steering apps with it's extra anti wear and FM's plus seal conditioners/swellers

 

And here I thought is was getting difficult trying to get the correct oil for an OHV pushrod non roller cam motor.

 

Just an update. I'm going with waiting until January. It's been running fine up until this morning. I checked and there are no codes for the transmission. This morning when it was cold, when I shifted into reverse it started again. I shifted back to park and waited. The light kept flashing.

So, turned off the key and restarted it. No light. I waited a couple of minutes and everything worked. I do believe it is temperature related. I will update after I get the fluid changed. Thanks for all the advise. It's been interesting watching the discussion.