Hi Lew,
I recently used a product called U-COAT-IT. It is a water based epoxy. It is very durable and made for heavy duty garage use. The product coast about $250.00 for a 25x20 foot floor. If you want the gloss finish and speckles it will cost about another $200.00. I used the medium gray without the gloss coat and it looks super. I have rolled my cars and engine stands over it without a problem. It is used in the garage area at the Carlisle PA fairgrounds where they display the indoor show cars. Here's the U-COAT-IT website.
http://www.ucoatit.com/ . As with any of these products the first step is to degrease the floor where
oil has spilled. Do that twise and also degrease the entire floor with a diluted mix. Then you must use muriatic acid to etch the floor. This process is done at least two times. These are the important steps to make sure that your product will adhere to the concrete. If you want to buy your degreser from U-COAT_IT you can but I just went to home depo purchased and one of there's. Muriatic acid is bought at either home depo or a hardware store or pool supply place(strong stuff). You will like your garage a lot more when it's done and also know that you are keeping moisture out when you coat the floor because moisture seeps up from the ground and through the concrete. Good luck and email me if you have any further questions, Sal.