Thanks for your thoughts guys, The engine is tuned up, and no black smoke either. I used 10W-30 oil when I changed, The mileage is 140K, Of course, it might have run more than that probably because the seller has changed the meter. The car oil indicator did not warn me about this I think the bulb was removed too, So I plan to top up the engine with the same oil and take the car to the garage. I will update you guys with their opinions.