Seems I have read before that diesel fuel additives are not necessary as long as you buy from high volume suppliers. But, I am having fuel pump issues on my 2004.5 and as part of the research on how to change the pump, it was mentioned that over time the pick up screen/sock can become clogged with what might be algae or some other diesel issue. Since I always use the high volume suppliers, I now wonder if I should be using an additive on both the new and older truck. Seems those that do add are saying they don't have a problem, but then maybe the problem is just a worn out pump. It's making a gurgling sound and does not shut off like it used to. No driving issue yet but I'm sure that's coming. About 127K on the odometer on the older truck. So if I should be adding something, any suggestions on what should go in and what maybe should not given we have different fuel filters on the newer trucks?