I bought the "Black Smooth Leather" style.  The leather grain is very tight and smooth.  You do not oil this style of leather.  You polish it with shoe polish.  These boots were too tight when I bought them and breaking them in was not helping any.  I ended up cutting the tongue on both sides where it attaches to the inside of the boot. That was enough to solve the problem.  They now fit like butter and look absolutely great with a fresh polish.