The reason not to put oily clothes in a front load is because the last rinse water is partly reused in the next load. And honestly, the water you use in a front load today has remnants from washes of long ago. It's just the way it is set up. Even a top load always has some water left over but the front loads have a LOT of water left over.
I owned a used appliance business and we always had washers torn apart repairing them. Another thing to remember.... used front loads are VERY hard to work on and the parts are very high priced, even for repair guys. We quickly learned to not mess with front loads. Too much trouble and cost too much to fix.