Extract that shit. Here's a link:
http://www.bluelight.org/vb/threads...-(aka-cdub)-Megathread-third-time-s-the-charm
The only difference is that you don't have to use a huge amount of water for 4-5 pills.
If you don't want to extract but don't want to be taking unsafe amounts of APAP, the max you should of those is three at once, 3-4x a day (aka 9-12 tablets per day at absolute max). APAP doses should be separated by at least four hours, to boot, and this is all if you're not drinking alcohol. I'm not recommending that you take a whole bunch of doses of opioids per day for fun, I'm just telling you that's the most you should be taking with regards to the APAP. The truth is there's no real sense in taking more acetaminophen than you really have to IMO and very little is lost during the extraction process if done correctly. However, if you're a relatively new user then 15mg of oxycodone should basically be enough anyway.
For what it's worth, I think redosing/taking a "booster dose" of opioids by mouth follows the law of diminishing returns and is barely worthwhile.
If you drink with any regularity, the amount of APAP you can safely consume is less.
The only thing I wouldn't recommend is taking three Percocet as they are and then extracting one or two. Extraction works better with a decent amount of powder/extractable material.
edit: Just to be clear, this is a pretty conservative reply. It's not necessary to extract three Percocet, as I've already pointed out, and taking four isn't super likely to do much harm to a non-heavy drinker. However, once you pass the safe amount it's really easy to just keep going until all of a sudden you're just chewing up eight or ten Percocet. This is why I feel it's good policy to start extracting as soon as you reach/pass 1000mg of APAP in the amount of pills you're needing.