All very good information from Bob. Older engines already broke in need very little additive, but you will not hurt a thing adding some if you feel better about it. Diesel oil has been cut back just as the automotive oil has, so don't assume a engine is protected just because its diesel oil. Almost all racing oils still provide the need protection. Heavy valve springs, extreme lobe designs, and high rpm are what really need the additives. The old inlines with 80 to 90 lb. valve springs will last a life time with out it. Some race springs can have over 400 lb. with the valve open, you can see where that might wear a cam out!!!!
Joe
