Hello i have Mercury Grand Marquis 1993 and i've got a question How much oil must consume engine ? How much is norm ?

 

The acceptable industry standard is up to 1 qt per 1000 miles. That said, I disagree. I have had several engines that used very little to no oil between changes. If yours is not leaking or smoking but using oil you can slow this considerably by using a good full synthetic. Good syn oils maintain viscosity better and engines in good condition tend to use less oil over the same mileage as those with regular dino oil.