the frequency of adding antifreeze

207 1.6 140,000km How many km should antifreeze be added under normal conditions? Although I haven't driven a lot of kilometers lately, every time I check I see that the antifreeze level is minimized and I pour it to the maximum. I'm using the shell's red one. I will then calculate how many km decrease by 1. How much do you put in? How many km is this normal? I suspect there is a leak. Do you have any other antifreeze brand / color suggestions? Good evening.

There was a leak in your vehicle, check the hoses, check the radiators and the lpg water hoses, if there was a leak in me.

If there is no leak, the water will not decrease. Engine cooling water is closed-circuit, so depending on usage, decrease etc. should not be.

Normal gasoline, not LPG. If there is a leak, then we need to take it to the master? How much is the estimated cost?

We do not know first of all, let's see if he is missing from the water, whether the oil is mixed with the water.