Bought a 2013 Taurus SE V6 3.5 with 95k miles Oct 2017 it now has 101k miles I seen manual reads trans fluid change at 100k miles, it was owned by Walgreens mostly. It felt like twice from a stop in D when ready to pull out of my driveway it felt like a small slip and bump you know the same if I would had it in neutral and put it in D. Figured either low fluid or filter getting dirty (outside temp. around 70 both times about a week apart). Later checked fluid level it was in correct after about 30 mile drive in 80 degree weather, it's been around a month and trans been working good felt nothing else wrong. I recently found out I can NOT replace filter, I intended to do drain, filter change twice. I've read that new fluid can remove old varnish build up which is going to be trapped in the filter that I can NOT change! Should I even do a drain and fill ? (read around 5 1/2 quarts) If those two slight transmission bumps I felt a several weeks ago was caused by a filter that's beginning to clog I'm I going to make things worse? I was going to use Valvoline Maxlife full synthetic atf does anybody have anything to say about that, like that's fine or noooo don't use that!!!!! I already bought it.