My old diesel mechanic used to only recommend Marvel Mystery Oil, or the Lucas product. I'd double-check with him, but he died in a car wreck ~ 10 days ago.
Mark, denoting old age here, for I have been using Marvel Mystery Oil in various specific applications for 66 years. Dad swore by it and got me going - it has been a big plus. especially for top-end lube on older OHV engines. I simply never connected that idea with diesel injectors - maybe because the Dodge Cummins is almost to 350K with nary an injector hiccup. We have only put about 6K miles on this 03 Duramax - it is at 108K well-maintained miles and I'm already fussing with injectors. Good and rather flexible diesel engine, but not near a Cummins 24V.
