We had this same problem. We are surrounded by 5 apartment complexes that would drain both of our
changers every weekend, with the local fast food and party store taking their share. We are now dispensing one dollar
coins for the larger denominations. We dispense like this:
$1-4 quarters
$5-8 Q/3 GD
$10-12 Q/ 7 GD
We still get some apartment people that will bring some one dollar bills in to get some change. Instead of having to buy upwards of $2000 in quarters every month, we are depositing about $1500/month. Unless you switch to all
tokens, it looks like you will have to switch out your acceptors if you want to accept multiple
coins.
MEP: I tried the sign at my wash, and it worked for about a month and then word got around that it was smoke and mirrors and then I was back to getting abused.