ATF +3 in 99 Concorde LXi 3.2 liter engine?

How big of a problem would I have after putting the ATF+3 (instead of the
ATF +4) in the 1999 Concorde LXi with the 3.2 litre engine?

I understand that I might have to change it more often than the synthetic
ATF +4, but I just don't want to be trapped into buying from the dealership.
It's supposed to have the same friction qualities, right? Just more prone
to long term issues than the synthetic?

 

Wrong. ATF+4 has a whole host of different operating characteristics. Your
cheapskate ATF+3 trick will very likely cost you expensive transmission
damage in the long run, regardless of how often you change the fluid. If
you refuse to maintain your car properly, don't bitch when it breaks. I
suggest you get over your aversion to buying the correct fluid.

 

Huh? (Assuming somehow you are not just trolling) if you can't find ATF+4,
don't fill your transmission with ATF+3 until you can get to a place that has
it. Tow the car if you need to. Using the proper fluid is absolutely critical
for these transmissions. If you want to save a few dollars right now, be
prepared to spend a lot of dollars to rebuild or replace your transmission
frequently not too far down the road. I don't understand your "change it more
often" rational either. ATF+4 has the friction and other properties that the
42LE transmission depends on to function. It was designed because other fluids
will not work in this series of transmissions and will quickly cause damage from
torque shudder and other problems. If you decide to sell the car, the least you
can do is fully disclosed that the improper fluid was used intentionally in the
transmission.

If you do decide to go the wrong fluid route though, you might be interested in
other cost saving measuires. For example, you can use K1 kerosene in your fuel
tank instead of regular unleaded. After all it can burn. Don't bother with
expensive API certified motor oil in the crankcase either. Vegetable oil has
some lubrication properties as well. Good luck.