About one third of all tasks that you need to perform on your Audi A6 C5 require it to be raised off of the ground. Simple enough for the experienced mechanic, the procedure of lifting a 3500lb. car can be a bit unnerving for the amateur. In this article, I'll start out by showing you the best places to jack your car up and how to support it while you're working on it.
Before you attempt to begin jacking up the car, make sure that all four wheels are carefully chocked, and that the car is on a level surface. Keep in mind that if you raise the rear of the car, the emergency brake no longer works (it works only on the two rear wheels of the car). If you place the car in park (automatic transmissions) or in gear (manual transmissions), it will only lock the front wheels. Place a few 2x4 pieces of wood in front of each of the wheels to make sure that the car will not roll anywhere when you lift it up off of the ground.
On the underside of the car and with your safety glasses on, you will see four reinforced sections along the body seam near each wheel. These are designed to fit the factory jack when changing a tire. This jack is meant to be used only in these situations. Never try to work under the car simply using the factory jack. For all other instances, you will want to place the car on jack stands.
You can use this reinforced area to place your floor jack. The downside to this is that you will have difficulty placing your jack stands, because you will be occupying the reinforced area with your floor jack. I recommend placing the floor jack in the middle of the car along the body seam. This will balance between the front and rear wheels due to the short wheelbase and allow you to place the jack stands and the reinforced sections near each wheel.
If you are lifting the front of the car, then place a jack stand under the front reinforced plate, lower the car onto the jack stand, and then repeat for the opposite side of the car. If you are lifting the whole car up off of the ground, then place a jack stand under both the front and rear points, lower the car, and then repeat for the other side. Likewise, if you are jacking up just the rear, place the jack stand under the rearmost reinforced point.
Safety is of paramount importance here. Never work under the car with it suspended simply by the jack - always use jack stands. It's a wise idea to use a backup jack stand wherever you place your primary jack stands. One tiny flaw located in the casting process can lead to a jack stand breaking - and having the car fall on top of you.
Once you have the car up in the air and supported on the jack stands, push on the car and see if it is unstable on the jack stands. If the car moves at all, you do not have it properly supported. It is far better for the car to fall off the jack stands while you are pushing on it, than when you are underneath it. Really try to knock it off the jack stands: you want to make sure that it's perfectly stable. Set the floor jack underneath the engine or transmission while you're working as yet another backup support. Again, it's a wise idea to set up a spare jack stand or two as a precautionary measure against one of them failing.
When you are ready to lower the car, be aware of where you are placing your floor jack. Sometimes you will not be able to easily remove the jack when the car is lowered. Or the jack handle may crush or damage an oil line or tube on the way down. Proceed very slowly, and also be aware that some floor jacks release very quickly. Also be careful to place the car in gear, or to engage the parking brake before you lower it. The car may have a tendency to roll away right after it is put back on the ground.
Front Wheels, Left and Right Sides: Note the reinforced sheet metal behind the front wheel (purple arrow). This section of metal is where you need to place the floor jack under when jacking the car up. You'll want to place the jack stand under the area highlighted by the green arrow.
Rear Wheels, Left and Right Sides: This is essentially the same as the front wheels. Jack from the reinforced section (purple arrow) and then place a jack stand under the area highlighted by the green arrow.
Shown here is the floor jack lifting the car on the reinforced area. It is a good idea to place some cardboard or rolled up newspapers between the floor jack and the jack point. This helps to distribute the load more evenly and prevent damage.