Hello, How many miles on your "new-to-you" car? Got maintenance records? Good luck with it! 6.1 qts. is the amount to go with. The oil cooler will have drained upon shut down. There's a designation on the back of most good oils' bottles called the ACEA rating. The ones with an A3 and B3 contain an additive for the turbo-charger's bearings. Those oils are 0W-30 synthetics and often say "European formula". Many on this board will advise against using a synthetic oil in a 12 year old car, claiming that the strong solvency of the synthetics will propagate leaks. Many others claim to have had no problems. What is Oil Rx (or whatever you said)? Check the oil seperator and flame arrestor for proper function. When they clog internal pressures build up and cause/worsen leaks. Both are replaceable maintenance items. DO NOT neglect the other fluids in your car. Multiple drain and fills work just fine for your transmission and P/S. Brake fluid and coolant need to be flushed. Post back with a few more details about your car like; mileage, evidence of dirt and leakage, interesting tidbits from a Carfax report, brand of oil filter you removed, condition of fluids and air filter. Give us some meat. Kira