I recently acquired a Mercedes Benz 300D (1993 w/om602 engine, 137k miles) and am wondering if I need to use a diesel fuel additive during summer and winter. This product is readily available in my area. Has anyone used it and care to report their opinion on it? I think I can even get it from Walmart. Diesel Kleen® +Cetane Boost® Diesel Fuel Supplement® +Cetane Boost® Thanks!