ah , it's hard to say , I called TOYOTA and was told they use whatever's cheaper at bulk at that time . Could be MOBIL Clean , ENEOS ( Nippon ) , or other . Sometimes I wonder if they use an additive to lubricate , clean ( or both ) the fuel system or engine or both from the factory during break in period that brings the better mileage after purchase . We've noticed this on all the TOYOTAs we've bought within the past 4 years . Seems more difficult to repeat those numbers like that when fresh off the lot during those 1st few tanks of gas . It's a bit of a mystery . MYSTERY OIL ? MARVEL as an additive at factory ? I just dunno . ;- )
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