i found this information on another forum. Hopefully you still have the old version of Photoshop CC because that is the only way to access the Oil Paint filter. Below is a copy of the message I found.
Hello, it is not available anymore in CC(2014) hence why it is installed side by side to CC.
The info was posted a few months ago: http://blogs.adobe.com/photoshopdotcom/2014/04/photoshop-spring-cleaning.html