Oil Painting

Open your image which you want to convert to an oil painting:

Press control+j to duplicate the layer.

Now, go to filter>stylize>find edges. As you can see, the find edges filter extracted the edges and more importantly, it embossed some areas of the image which are useful in oil painting :

Now, we will reduce this filter to have more realistic oil painting effect. For that, press ctrl+shift+f to open fade dialog box and apply these settings :

You can easily see that most part of the image are converted to oil painting :)

Press control+e to merge these two layers. Press control+j to duplicate the layer and press shift+control+u to desaturate it :

Now, change its blending mode to Multiply. Our image is now converted to an oil painting, but still it lacks contrast. We will use levels to increase the contrast of our oil painting in next step :

Again press control+e to merge the layers. Press control+L to open levels dialog box and apply these settings :

You now have an oil painting of your image :)