A couple of times over the last three weeks or so my wife's 1998 ML320 has failed to start in the morning after sitting overnight in sub-40 degree weather. When you turn the key, all the instrument lights come on, as does the fan, but there is no start. Not even a click. Trying five or six times yields the same results. Now for the strange part. I switched on the headlights to verify that the battery is not the problem and voila! The engine cranks properly with the headlights on. In each of the cases where the engine would not start, switching on the headlights first then trying to start the vehicle cures the no start condition. Any ideas?

While changing the oil this afternoon I noticed milky-tan colored deposits on the bottom of the oil cap and on the upper part of the filler neck. I checked the drained oil and the coolant and both appear to be good with no cross-contamination. I have heard of this before on some other vehicles where moisture-laden air enters the cylinder head and condenses on the underside of the cap where it mixes with oil. From what I can remember, this happens with vehicles that are driven on short journeys where the engine does not always reach its proper operating temperature and burn off the water moisture. Anyone else have these deposits?