Why do some coolants don leave stain marks?
Some coolants DONOT have the extra Special Rust Preventive Pigment which forms a coat (like Paint) over the inner part of the engine. The metal parts where the coolant comes in contact starts rusting when not in contact with the coolant. So Rusting, Scaling & sludge formation takes place in your engine, blocking the coolants path thus overheating the engine & reducing the performance of the vehicle.
