Originally posted by Johncathleen
Thanks much for this info. Offhand, can you think of other reasons why we might be losing oil. I am going to check oil-sender unit, seals, etc. but there are no stains under the car where it sits, so if there are leaks, they are only while it is moving down the highway.
the best way to check a headgasket is to get a compression test...this will tell you what max compression you can get from all 4 cylinders...since you are losing both coolant and oil it is most likely an internal leak into one of the combustion chambers
take out each spark plug and look at it...if there is white residue on them then that cylinder is where the leak for the coolant
another more thorough test you can do is a leakdown test that will give a more accurate test on how well your car handles compression...it can tell you if you have a leaking piston ring or a damaged cylinder wall (allowing oil in the combustion chamber)
but is is most likely a headgasket as you are slowly losing both fluids...i'd suggest repairing it as it could go anyday with average driving...causing the engine to overheat the warping the cylinder head (getting it to hot so that it is no longer flat)...while that is being done i'd get the thermostat ($30), water pump ($50) and timing belt & pretensioner ($70 together) done at the same time as they will have easy access to it