2008 X5 4.8i. Looking for some recommendations for the following parts that I am replacing while rebuilding my engine. My alternator is functioning normal but has been covered in oil for months. My water pump gasket failed miserably, my belt tensioner (black pulley part only) is in bad shape, and I figure it is time to change the thermostat. Any tried and tested recommendations for replacement brands/manufacturers for these parts? Since I am replacing so much on my engine I would like to save money where I can without losing quality. I appreciate any recommendations. There are several brands for each part.