My audi a4 1998 is running out of oil and anti-freezing very fast. So the motor over heats and the console dont stop beeping, help please

The whistling noise is steam. The problem is you never attacked the source of the problem. What you need to do now is drain your radiator completely at opening T-spicket at the bottom of the radiator. While you drain with engine off, run your water hose on top, to flush out the radiator. Then run to the Auto store and buy "radiator flush" -- follow directions. After flushing out the radiator flush, close the T-spicket, and fill with NEW anti-freeze. By enough to fill to the very top. Mix the anti-freeze with water per instructions to your environmental weather.
Buy a new radiator cap which could have caused the problem in the first place by not allowing the correct pressure to blow off. Being a 2000 car is a little early for radiator problems, but an incorrect anti-freeze solution causes radiators to fail prematurely.. Better to have more than less because anti-freeze keeps the radiator from corroding.
Your radiator never cooled the water sufficiently, and boiled much of the water out, hence it got so hot that it would melt the water tank. The Thermostat could well have been the cause because it got corroded from the inept ant-freeze mixture. Did you find rust on the Thermostat ? If so it was the case. If not the radiator has lost cooling either by low water or the cores have become plugged up, in that case you will need a new radiator. See if the flush loosens the rust within the cores before buying an expensive radiator. Check the water hoses if leaking cooling. Run the car allow the engine to become hot before accepting that your water hoses are fine. Because heat expand everything, and may not leak until after the expansion.

is it 5.7l

My thought is that you probably have a blown head gasket or a cracked block. I would have someone do a pressure test on the coolant system to determine where the leak is. Doesn't sound good.

When your not feeling heat coming from the heater it usually means that the coolant level is too low in the radiator. It sounds like you have a coolant leak somewhere which is causing your overheating problem. Fill your radiator and let the engine run for about a half hour with the radiator cap on tight. Then turn off the engine and check for any leaks under the van. If you don't see any leaks under the van then see if the carpeting is wet on the passenger side of the vehicle. If the carpet is wet and it smells like anti-freeze you have a heater core that is leaking. I hope this helps you. :)

You should have found the oil floating on the top of the radiator, A compression check will tell you real fast if the head is blown and even tell you which piston it is, The exhaust should have steam in it. Hope this helps.

check the lower rad hose , it may be collapsing, it should have a spring inside to prevent that problem, overheating only when the engine is run at higher rpms

I have seen a couple of these now with headgasket leaks to the outside of the block just as you describe. I solved them both with a stop-leak additive, not something I would normally use, but I really didn't want to pull the heads because the exhaust studs always break on these engines. I would find out for sure where the leak is before proceeding though. If it's a hose or frost plug, you'll have to repair it properly.

When is the last time you got an oil change? Did they reset the system? The light may be trying to let you know you know you need an oil change,

I took thermal stat off car again,place it in hot water till the stat open(to see if working).Place stat back in and not put the housing back on,disconnect the top hose,pored anti freeze into hose.Anti freeze started to drip out of thermal stat,as I was filling head the air was being pushed out.I could hear like a whistle,when whistle sound stopped put thermal stat housing on,hooked hoses up.did not over heat and have heat in my car now

g 12 is the only antifreeze you should use in that engine