My antifreezeneeds filling every other day, it's had a air pressure test and the garage says there's no leak.What could be the reason for this please?
Coolant loss can be from a few reasons. It may have a leak that is small enough that it takes a day or so to drop. have the repair shop try using the pressure tester to apply 12 psi of pressure and let it sit for a couple of hours. The radiator cap can be bad. If it is not sealing tightly, the cooling system will not reach it’s required pressure and coolant can leak and boil off as you drive, so it may never hit the ground. There can also be a gasket issue, either intake manifold or head gasket that is leaking coolant into the cylinders in a small amount. The spark plugs should be pulled and inspected. If any of them are a light whitish color, that indicated coolant is getting into that cylinder.