I have been using the same oil for over 2 years. It is good for 10,000 km, although I change it after 7,500km. At 3,750km I change the oil filter and then again oil and filter change at 7,500km.
The oil is great. Haven't had any problems ever since I started using it. And now my 96 Civic's engine has done over 223,000km. The engine has never been opened ,still running on petrol and compression tests show that it is still going strong. I still take it close to the red line every now and then
But I think you're mistaken about the price. The 4 liter bottle sells for 3700, that's what I paid for it when I last bought it a few months back. Just make sure you are buying from a reliable source. And after you have used the oil, cut the bottle to shreds before discarding it, because there is too much fraud. Oil is cleaned and refilled in the same bottles to be resold as new.