What are the advantage of a vertically mounted oil filter vs. a horizontally mounted oil filter?
With a horizontally mounted filter the oil will drain into the crank case and upon start up of the engine the oil filter must fill up with oil, flow through the lines and start lubricating the engine giving you a longer dry start up. With a vertically mounted filter the oil remains in the filter and will pump through system for a quicker lubrication on start up. The other advantage is you can fill up the filter with oil without the mess again for a shorter dry start period. Removing the filter without the mess is also a good thing.