Residue in oil fill cap likely caused by moisture

  • Article by: Paul Brand
  • Star Tribune
  • March 27, 2011 - 1:47 PM

QI hope you can give me some advice. When I took my 2005 Ford F-150 (a 5.4-liter Supercab with 74,000 miles on it) in for an oil change, the mechanic asked if I put a stop-leak additive in it because he found cream-colored moisture in the oil fill cap. We have not put stop-leak or anything else in it. He suggested doing a radiator and compression check. Should I?

AThe milky, cream-colored "gunk" in the oil filler cap is probably moisture condensing in the crankcase and mixing with the oil. This is relatively common in colder weather. As the engine warms up, the moisture in the air inside the engine condenses into liquid form and mixes with the circulating oil, leaving a milky residue on the dipstick, inside of the valve covers and oil filler cap.

This condensation will be worse if the engine does not fully warm up due to relatively short drives and/or is not driven long enough -- 20 minutes or more -- to reach full temperature and evaporate the internal moisture.

The first test should be the thermostat to ensure the engine is warming up to full operating temperature. Longer drives and more frequent oil changes will help clean out this residue before it has a chance to turn into sludge.

QWe have a 2002 Ford Taurus with electrical problems. Our car will work for several weeks, and then suddenly the battery goes dead. The courtesy lights will not shut off about 25 percent of the time. We have to cycle through the lock-unlock process several times in order to shut them off. On two occasions the lights were off when I left the vehicle, but on when I returned. We often find it necessary to rotate the dimmer feature to "lock on, lock off" in order to turn the dome light off. My mechanic suggests replacing the courtesy lamp relay.

ABoth the courtesy lamp relay and the general electronic module (GEM) are under the dash on the driver's side. The relay provides power to the courtesy lamps, and the GEM module controls a variety of features, including the courtesy lamps, interior and exterior lighting, keyless entry, wipers, power windows and more.

But before replacing either of these, have your mechanic test the ignition switch itself. Any worn or intermittent contacts in this switch can cause the type of symptoms you've described. If the relay or module were at fault, a fault code should be stored in the GEM module.

QIs it dangerous to use the cruise control as if it were the gas pedal?

ADepends on what you mean by "gas pedal." First, cruise control systems are not designed to allow engagement below 30 miles per hour, so it's not possible to "drive" the car around town using the cruise control "accel" button. Above that speed, if the cruise control is engaged it is possible and acceptable to increase the vehicle's speed by pushing or holding the "accel" button. There's no particular harm doing this, and it saves having to accelerate the vehicle with the throttle pedal to the new, higher speed and then having to set that speed by pushing the "set" button again.

Of course, to lower the vehicle's speed you have to either push the brake pedal or disengage the cruise control. If you slowed by pushing the brake pedal, the "resume" button would accelerate the vehicle back up to the preset speed.

In essence, the cruise control is designed to allow the vehicle to maintain a preset speed with the driver not having to hold the throttle pedal in a fixed position. The "accel" button is designed to accelerate the vehicle to a higher "cruise" speed without having to use the throttle. But this button is not designed to be a substitute for the throttle pedal in normal driving.

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