I use Badger Needle Juice (Regdab)... it is a lubricant for the needle/trigger assembly to make a smoother pull on the trigger. Coat your needle with it and it will help retard paint sticking to it, and prevent needle dry.. (when spraying acrylics you can look at the tip and see dry paint building up on it... eventually this will disrupt the airflow, hence the pattern that is sprayed) Iwata makes Medea Super Lube. Both are available at some LHS's and art stores (not your Michaels/Hobby Lobby type) more like the upscale ones that sell 20 dollar paint brushes and such.. dont worry it's less than 5 dollars a bottle.
If you just bought your 155 may I recommend you buy one or two extra needles (it will bend eventually, it never fails... $4.50 each from
dixieart.com. and a bottle of lube, about $3.50... follow the directions on the bottle, but also take out the needle and coat it... (not sure everyone does this but I do) it's easier to move up and down the spectrum of paint flow with the trigger lubed with that stuff.... should last you awhile as you only use 2 or 3 drops per application...
if you're married, you can order the same needles and lube from greatmodels.com, and throw in a model or two to offset the cost of shipping (memorize that story for the wife, she may buy it
)