Any new locomotive I have I add 10 to 20 drops and let it sit for 10 minutes or so. I add another 10 drops after that and let it sit for another 10 minutes. I then add 10 more and run it. You have to get that batting material soaked with alot of fluid. The recommended 15 to 20 drops is just not enough in a fan driven smoke unit that is new or dried out over time. Once you have a nicely saturated wick the 15 to 20 drops works. If your train has been sitting a while it's time to start the process over. This has worked for me great so far.
Brad