For cleaning the pennys I did try the coke but it took too long and did not come out really clean. I just found out this morning if you use the silver dip cleaner it comes out clean within 10 seconds. It was amazing. I just cleaned a whole bunch of pre 1982 pennys for our trip.
Here's a simple science experiment trick you can use to clean up your pennies.
1. Put the pennies in a dish or pie plate.
2. Sprinkle some salt on top of the pennies.
3. Add just enough vinegar to cover the pennies. In less than 30 seconds you will have bright shiny pennies
If the pennies don't come clean enough for you the first time, leave them in the vinegar and just use your salt shaker to sprinkle a little more salt on top of them. You may have to do this when you flip the penny over to clean the other side.