Hello Bob and friends! Forgive me if this is redundent. How ever 0w-16 is on my mind If 0w-16 has ben used since 2000 , can it be used in older engines? i tried it on my 2009 KIA spetra and the engine runs great . Will check milange soon . It loks like I will get 2.mpg more but am I ruining the engine? should I go back to 0w-20 or 5w-30 . help me you learned engineers!?