do i have to use 5w20 motor oil

You don't have to do anything, but, what does your owner's manual recommend??? If you care and you should, follow the instructions.

173,500 miles. I would ignore Mark and the owner's manual and run 5w30 in a name brand conventional oil changing it every 5,000 miles or 1 year whichever comes first. I personally use MotorCraft Synthetic blend available at you local Walmart for a good price.

Well, my remarks were rhetorical, but, again, you've gone 173,500 miles on the current oil recommended so that's worked pretty well for you...My question is what's going on that requires you to change what you are doing?? If you are burning oil or have worn rings and valves, going to a 5-30 may not help you out that much,. If you are burning a lot of oil, you'll likely continue with this problem until your car is fixed..... And, 173,500 miles is a lot, what are you complaining about? I'm sure that you can go to about 200,000 miles easily, after that, it will require more attention.. Good luck.

some 05 call for 5w30 and some call for 5w20 same year same engine

Mine has 222k and 5w20, no matter what. Even a mrchamic recommend me to go to 5w30 or higher. There should be a reason why Chrysler engineers and its staff say that.

Hahaha lol

I've owned and worked on Chrysler Vans Caravans Dodge four years and I've always gone with the owner's manual recommendation or factory as of 3 years ago I now own my own Chrysler Town and Country 02 3.8 engine when I purchased it it had a 138,000mi on it the previous owner had taken care of it perfectly the minute I saw the engine and heard it run you could swear it was Fresh Off The Factory floor clean no oil anywhere he gave me a maintenance list of everything that was done to it including the oil change schedule and I follow that up to this day and it's still running as well as it has been since I purchased it. I am a lover of cars engines I Marvel at the preciseness and Precision in which they are engineered I'm saying all of that to say this since I've owned my 02 Town and Country I drive to Texas once a year I live in Milwaukee Wisconsin that's approximately little over 1,600 miles away 17 hours of driving it simply runs like a Swiss watch without a hitch I've even pulled over on the side of the road pop the hood and just look at the thing run as a result of my traveling my engine is at 175000 miles and and till this day you have to hear it run to believe what I'm saying and at the oil change spot where I go the manufacturer for my van recommends 5w 30 the previous owner used 5w 30 so I've never had any reason to change to a different oil weight there's an old sayin if it ain't broke don't fix it