Its on 10w30...i've also heard that older cars should run on thicker oil..is that true?

Hey guys,

Here is the details of the car

Chevrolet Optra 1.6
Semi-synthetic Rockoil 10w30

We recently bought this car as a third car because I started doing my internship and we needed an extra car.During the first week fc was at 7.6 km/l and so we changed engine oil and filter as well as the spark plug cable as the foreman said on of the cable has  no voltage. After that the fc seemed to improved to 8.5 km/l although its not something to shout about. But yesterday all of a sudden 100km = 15.7l which is roughly 6.3km/l. This us just freaking high for a 1.6 car. We use either petronas or shell. And please give honest opinion instead of korean car,old car,etc. Any experienced opinion is highly appericiated. Btw mileage is 140000km. And I drive moderately 2k-3k rpm.

What do you mean by this, all of a  sudden? If you're looking at the meter, it's not accurate, because that is a realtime thingy. You should take a full tank, run it until at least half empty, then pump fuel and calculate km drove / litre used.

Anyway, if 6.xx km/l, it's normal in city jam with a high FC car.. Remember, in jam it's  0 Km/l...fuel get used up and you are going nowhere...the longer you get stuck in a jam, the worst it will be. Nothing you can do about it.

I owned one for 7 years. FC is about 11 to 12 km/l
I think you have faulty fuel gauge sensor in the fuel tank.
Always showing error volume of fuel like mine did.
Change it. About RM 160 at SC.

At first i fill up till full tank and reset the trip meter...once it reached 100km, I fill up again and record the litre needed and do the calculation..so its a legit calculation and nit dependent on the fuel gauge errors