generally, the rule of thumb is every 1qt of oil per cylender. thus, for 4 cylender engine, 4 qt, 6 cylender engine, 6qt, and 8 cylender engine, 8qt. prepare one extra bottle to top it off when needed.

besides, get a quote from ur dealer for an "out of parket" oil change in between service. My dealer quote my $85 for an oil change. if you add all the parts together for an oil change, (6 to 7 bottle of oil, oil filter, air filter and other fluid top up) i think $85 is pretty reasonable and you can save the trouble of going under the car and get ur hands dity.