Motoring Q&A: Truck owner unsure about block heater, synthetic oil

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Columbus CEO

QUESTION: I have a 2006 Ford F-150 with the 5.4-liter V-8 engine. The truck has only 32,000 miles on it. When the oil is changed, sometimes it is somewhat milky. I know this is most likely from cold morning starts coupled with a two mile drive to work. The engine barely has time to warm up. My question is the use of a block heater overnight when it is extremely cold. Will the heat from the block heater cause engine condensation? The heater makes a huge difference in ease of start-up and the engine warms quicker. Should I not be using the block heater? I started using synthetic oil as well.

ANSWER: Entirely appropriate question with the recent spell of frigid temperatures across much of the country. I’m a firm believer in engine block heaters in areas where temperatures drop to zero or below. The benefits of easier cranking, faster starting, lower stress on the starter motor, battery and engine and faster lubrication to critical components far outweigh any — well, I can’t think of any downsides.

Condensation inside the crankcase is going to occur during cold weather starts when moisture in the air inside the engine is rapidly heated upon start-up. The only way to eliminate this moisture is to drive the fully warmed up vehicle long enough to evaporate and expel the moisture through the PCV system. In addition, more frequent oil changes during cold weather can be a useful tool in removing moisture and fuel contamination from the oil.

Does using a block heater contribute to higher levels of moisture contamination? I don’t know for sure, but the fact that a block heater slowly warms up the engine, coolant (and to some extent the oil) and maintains that temperature would likely contribute little if any additional condensation.

Thus, I think your use of synthetic oil and a block heater is a very solid game plan for winter.

Q: I have a 2007 Dodge Grand Caravan. If it sits three to four days without starting, the battery is dead. I have taken it to the dealer several times and they cannot find anything wrong with the charging system. Their reports states “tested for excessive IOD and it is at 14ma and well within spec. Saw the IOD jump to 3M randomly for just a second but never above the max spec of allowable draw.” They advised to “pull the IOD fuse” when planning on not starting the vehicle for a few days at a time. They also told me that this was normal, which I find difficult to believe.

A: This is not normal. Your first test should be to disconnect the battery while the vehicle is parked, then after three or four days reconnect it and see if the vehicle will start. If not, the battery is not holding a charge and needs replacement. This could easily be the issue.

If it does start after three to four days, there must be some type of parasitic current draw that’s draining the battery. Current drawn with the ignition off should not exceed roughly 50ma (.05 amperes). This level of parasitic current will not kill a good battery in a few days.

The “IOD” fuse in your vehicle controls ignition-off power to those circuits with KAMs — keep-alive memories. Removing this fuse will only stop current flow to those components but won’t stop a parasitic draw from some other source.

To find a parasitic draw, disconnect the negative battery cable and connect an ammeter or 12-volt taillamp bulb in series between the cable and negative terminal. If the bulb glows and/or the ammeter reads a significant parasitic loss, pull each and every fuse and relay, one at a time. Hopefully the current flow will stop when you find the circuit drawing current.

A small lamp, such as the glovebox light, or a stuck electrical relay would be likely culprits in a dead battery after several days.



Paul Brand, author of "How to Repair Your Car," is an automotive troubleshooter, driving instructor and former race-car driver. Readers may write to him at: Star Tribune, 425 Portland Ave. S., Minneapolis, Minn., 55488 or via email at Please explain the problem in detail and include a daytime phone number. Because of the volume of mail, we cannot provide personal replies.


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