The more you do the more you'll know on how much to use per repair. You will also soon not worry about it too much either. Let me just say that I paid for my kit with one bottle. Your returns out weigh the worry. You will soon see that. For just a if you need a number just use about 7 drops on each repair until you see how much runs out when you move the injector. If there is not much left you did good, if there is a lot, use less next time. I won't take long to work it out.

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