i hope you are not using that particular oil since i believe its synthetic and i don't think you should use synthetic in a diesel as a fuel additive according to other posts i have read on this site. i use tcw3 xd 25 evirude/johnson about 1 qt to a tank full. made a huge diffrence here as well.[/QUOTE/
FYI Johnson/ Evinrude quit making XD25 a few years ago. They replaced it with XD30. It's basically the same thing. Quicksilver (Mercury) Premium Plus is a synthetic Blend, part regular oil, part synthetic. Quicksilver Premium is comparable to the XD30. I wouldn't put Walmart, or any other off-brand 2 cycle oil in anything that I value. I have seen too many outboards and jet skis that use lower grade oils wear out prematurely.