[plain OM]

The flashing AT Oil Temp light is indicating that the transmission control module on-board diagnostics has found a fault.

The CEL on could be related to the transmission problem, or it could be for yet another problem, perhaps related to the engine.

The engine oil dipstick is notorious for being difficult to read -- there's lots of posts here about it and suggestions on how to get a reasonably good reading.

The oil leak could be from the pan oil drain plug, from the valve cover gaskets, from the "separator" plate at the back of the engine, from various seals etc. If you're losing a lot, especially something like 3 litres in a few hundred kms, find out where it's leaking because you could lose the engine if it's driven with too little oil.

The (!) and BATT lights coming on at the same time usually mean the alternator has stopped working. You were able to continue driving for a while on the battery, but there wasn't enough left in the battery to restart the car.

Sounds as if the car will need a fair amount of work to get it into some sort of reliable condition. Do some reading of the threads using the Search function to narrow down the information on individual symptoms. There's a lot of information already available here, and we'll all try to fill in any gaps in response to your questions.

 

[plain OM]

Not much point installing a new battery without checking the alternator and the wiring, both of which can lead to a dead battery. (By the way, there's no "negative cell" that I'm aware of; not sure what they meant other than perhaps the battery was dead.)

If I'm reading the thread correctly, it was only two days ago that the oil was topped up because there was no indication on the dipstick; now it's back to the same thing. Sounds as if there's a really large leak. You won't get very far, especially if you want to go camping etc, with that type of loss, on top of the other issues the car apparently has.

From the sounds of it, there might well be other problems, especially on a car with that many kms; for example, suspension, steering, brakes, tires, etc. it might be an idea to have a mechanic assess what needs to be done to get the car into reasonable, and safe, operating condition.