I have to add 1 liter oil for each 1000 km. to my corolla 2001 vvti. And when increasing the speed I hear mechanical rattles.

Bummer Lito, the next areas are valve stem seals and then rings.

Pull the oil cap while the engine is idling. High pressure is blow-by from the rings. Low pressure, look at stem seals.

Yes it is normal. computer adjusts the RPM's.

is is odometer reading?
all cars burn oil if driven real fast, at 80mph, lots.
what i need is ,
1: speeds driven. avg.
2: and what weight, oil , is it hot there, sure, then run 10w-40 oil.
3: how many liters of oil per miles.
some cars go for years, burning 1quart of oil per 3000 mile.s
1L/5000 km to 1L /1000 km. (new car to old)
even more. on older engines.
if the engine runs good, drive it and change oil more often.
check oil at every petrol fill up, and learn what your engine needs
all engine burn oil by design. its a fact.

do an engine compression test.
2 times wide open throttle.
on a warm engine
if lower that spec, 150psi?
then add 1 teaspoon, of oil to spark hole , see if compression rises
if it does, its rings are old.
post the numbers, if all are 150 or more , drive it like you stole it.
half joking there, but drive it. and change oil often and check oil levels
every fill up or every other (depends on reality)

GASKET.
post the compression test readings. only NUMBERS count.
we need numbers and engine size.

- Engine oil change:
Engine oil- fully synthetic. 5W20, SN. Replace oil after every subsequent 5000-8000 Km.
- Replace oil filter after every subsequent 10,000 Km. (Genuine).
- CVT, Transmission oil change. CVT-TC 08886-02105.
Replace CVT oil after every subsequent 100,000 Km.
- Replace Toyota coolant after every 30,000 Km.

Sounds like a bad rod bearing, no cure except a rebuild. I assume you do know the difference between spark knock and bearing knock.

STP won't stop the leak, only disassembling and replacing the seal. However, the car could be burning oil but the catalytic converter will complete the combustion of the 'smoke' to water (H2O) and Carbon Dioxide (CO2).

At 230,000 KM, I wouldn't be surprised that the rings are worn or the valve seals are leaking internally.

oil leak

The oil light may be defective, but make sure that you have enough oil pressure @ idle. It will not matter how much oil is in there if there is no pressure. If the pressure is low, it is either the oil pump, or the oil system is clogged up somewhere like at the pick up tube at the bottom of the engine block.
There is a solution that you can add to your oil to clean the system. You have to run it a few miles and change it.
Pressure increases with RPMs.
Good Luck.

First it could be anti-rattle clip on the brake pad clattering. If it's louder when you turn, It is likely the CV joint needs replacing.

I have been having a similar problem (2001 1.8-TDI Beetle). The rattling sounds almost like wind buffeting the car/whistling, and increases in intensity as each gear revs higher (it gets quieter after a shift, and then builds again). at its loudest (before a shift), there's an additional rattle similar to tin cans in a paper bag being shaken (it's faint, but it's there). I just had the oil changed and the car looked over... not sure what could be the problem, but would like to have even a vague idea before I take it in. Any thoughts? Thanks!