I maintain my 97 Neon, & look after my Mom's 94 Grand Marquis.
A couple of days ago I checked her owner's manual. It mentions only 5w30 weight motor oil- it's "preferred".
I always go with 10w30 or 5w30 oil for it, even used 10w30 all through this past winter. Right now has Pennzoil 10w30 in it, will get changed in a week or two to Havoline- 10w30. I'll use 5w30 next winter, I promise!
winters are usually mild enough here that there's little practical difference between 5 & 10 w30.
My Neon's manual mentions other weights, I've even used 0w40 in it, but mostly it sees 10w30 or 5w30- even the Neon manual says that 5w30 is preferred. Right now it has almost 1000 miles on some Formula Shell 5w30 dino with Auto-Rx in it. I'll rinse with FS 10w30, then do another clean & rinse, also with FS- but will have to check my stash for which weight.
So, do I always follow the reccomendation? Well, sometimes I do, sometimes I don't.