Q&A

By air coming out the oil filler car what I am assuming they were talking about was the engine had excess "blow by". Your engine has pistons that travel up and down in the cylinder bore. Power made in the cylinder bore when the gasoline explodes transfers this power to the pistons and on to the crankshaft producing power that ends up out at your wheels. Blow by occurs when the power produced in the cylinder leaks down past the piston's side and does not transfer all the power to the piston. Efficiency is lost, emission/pollution levels rise ,the engine burns and leaks oil.
The usual cause of this is infrequent oil changes, an engine that was run low or out of oil, high mileage, or over heating.
Have the rest of your car inspected and acessed to find out if it worth investing in a new engine. It would be awful to put in a new engine only to find out the gear box is also bad, or the car needs major brake work or has serious rust, or other costly repairs in the near future.