Q: White milky stuff in oil cap and loosing coolant around two cups a week

If you have a continuing coolant leak, and the leak does not appear to be external, there is a possibility that coolant is leaking into the crankcase. Depending on the engine design, such a coolant leak could be via the intake manifold or the cylinder head although there are some other unusual possibilities involving cracks in the head or block. If the leak were through a faulty gasket in the intake manifold, it is more economically repaired. If you desire to have this evaluated, that is have the cause pinpointed, the relevant service to request is a coolant leak diagnostic. If you request that diagnostic the responding certified mechanic will get this resolved for you and let you know what the repair options and costs are. If you have further questions or concerns, do not hesitate to re-contact YourMechanic as we are always here to help you.