If you have oil in the LP lines, it is coming from the LP tank, meaning you somehow got a batch of LP with excess mercaptan oil (the stuff that makes the unique smell), or some type of contamination. Water in the LP also makes for oily globs that can get sucked into the lines. Changing out the regulator doesn't fix that, so if there is still goop in the tank, you may have repeat problems until you get it all. In bad cases, the tank may have to be emptied and cleaned.
Try cleaning the trap if it has one, and replace the regulator again if it too is clogged. If it happens a third time, you may have to pay for a tank cleaning.
Former owner of 2004 American Tradition
Home is in the Ocala Nat'l Forest near Ocala, FL