Berryman B-60 High-Mileage Oil System Rejuvenator (part #7517) is intended to be added to your high-mileage vehicle’s oil halfway through your standard oil change interval in order to “reset the clock” and then remain in the oil until you change it.  In essence, 7517 is formulated to breathe new life into your high-mileage oil so as to give you 150% of your standard oil change period.
 

What that means is if you use a conventional oil that you change every 3-5k miles, then you would add 7517 at the midway point of your choosing and then drive another 3-5k miles.  Likewise, if you use a full-synthetic oil that you change every 8-10k miles, then you would add 7517 at your preferred midway point and then drive another 8-10k miles.