G. Oil & Fluids
Mobil 1. Not a lot more to say on oil really.
The procedure if you want to do this yourself is really easy. Get a decent plank of wood, about 2" thick, and reverse the rear right hand side of the car over it so the rear wheel is sitting on top of the wood. This gives you enough space to slide the majority of floor jack types under the jack point on the rear right. (I used an 2.5 ton jack borrowed from a friend. Thanks, Joe!) Properly and safely secure the car with chocks under the other wheels and start slowly jacking the car up. When you've established that you've got enough height to be able to slide under the rear or rear/right side of the car, again make sure the car is safely secured. Some use jack stands for this.
You'll need a flat oil collection pan with at least 12 qts capacity, an 8mm wrench socket for removing the oil drain plug, a filter removal wrench (ideally one that fits the filter housing and allows a separate rachet to attach to it - I didn't know the correct size and simply used an adjustable jaw wrench), and the various parts - namely, new filter (which comes without an external housing), o-ring for filter, a new aluminum washer (for drain plug), and a probable max. of 9 qts Mobil 1.
Removing the drain plug was easy but take care to properly insert the socket - the plug seems to be made of aluminum and you'll damage it easily if not careful. Drain the oil, taking care not to get scalded if it's still hot. (You may also want to wear latex gloves as used oil is carcinogenic.) Once the oil is drained (I waited until there was a steady drip rather than a flow as such), you're ready to remove the outer casing of the oil filter which is located just forward of the drain plug. Screw this off to reveal the filter and note that there will be plenty of oil in the casing as you pull it away. The filter itself can be pulled off either directly by pulling downwards or by twisting and pulling down. There are no threads or anything, just a phallic-like head that pushes into the filter's top. Replace the filter by pushing it up and over the knob and screw the old housing back on, with lightly lubricated o-ring (easier to get it on if it's slippery). Replace the drain plug and use the new washer. You're now ready to pour in the new oil. Several people have suggested mixing two different viscosities of Mobil 1. I believe Van Larson might have been the first to post on this and he was also the first to explain a 996 oil change in any detail. (Thanks, Van.) Pour in 4 qts of 5-30, followed by 4 qts 15-50. If you need to top off, add very slowly, more 15-50 but don't over-fill or you might have to drain the whole lot! Lower the car to normal, start her up, and immediately check the oil pressure, which should be right up at max. Also check for any warning lights. If there's a problem, something's leaking, you haven't put the lid on something properly, or you've somehow dramatically underfilled the car. Checking oil level means getting the car up to normal operating temperture. Take it out for a spin, periodically checking pressure, and when warmed up, stop, turn off the engine and check the dip-stick. It is not advisable to exceed the max mark on the stick and some have reported (Bill, actually) that excess oil can be a cause of oil leaks from the main bearing seal.
Disposal of used oil is regulated by law in most places, so its best to find out where you can legally dump it. Most auto parts stores have free disposal tanks.
Check out http://www.boxsey.com/ and under Projects you should find a section on changing oil. It's on a Boxster but is roughly the same.
The oil change interval is a matter of up-bringing, religious conviction and/or happenstance. The recommended interval is either 10,000 miles or 15,000. To be honest, I can't remember which it is - you'll just have to look it up in your Service Guide or call the dealership. I personally change oil after 10,000 and will change regardless after a school/D.E. Some say changing the oil after the initial 3-5k helps get rid of new engine particles and other ware-in stuff. I did my first change at 5k, after a DE event. One good rule of thumb - it is probably worth changing the oil at least every year regardless of the mileage done.
Other fluids: Well, ATE Super Blue (and other colors to help you gauge when you've swapped out the old stuff) for the brakes is liked by many. Its higher boiling point prevents fade during track time. There are other products that have even higher boiling points. Redline products are also liked by many and their WaterWetter fluid, which mixes in with your coolant, might just keep your temp under control if you've been running too hot.