THE GOODS : His Kind of Blanket Insurance Won’t Do
Question: This letter is not a joke. My in-laws in Spokane have a 15-year-old Honda Accord with fewer than 40,000 miles on it. On a visit, I drove it around and smelled something. When I looked under the hood I almost fainted. My father-in-law had covered the entire engine with a heavy wool blanket. When I told him it was a fire hazard, he snapped, “All cars are fire hazards.”
I removed the blanket, but I am confident he replaced it after we flew home. My father-in-law knows a lot about cars, but this can’t be right. What do you think?
Answer: Although covering an engine with a blanket certainly seems bizarre, your father-in-law is probably hanging onto a folk remedy pioneered in the 1940s.
I suspect I know what he was trying to prevent. With such low mileage in a climate that never gets terribly hot, the engine could develop moisture condensation in the crankcase.
As an engine operates, a small amount of combustion gas passes through the piston rings and enters the crankcase. The gases contain moisture, and during a cold start this moisture condenses and mixes with the engine oil.
Normal use of a car results in the engine oil getting quite hot and boiling off the moisture, which is then drawn away by the crankcase ventilation system and fed back into the cylinders. But if the car is used only for short trips, the moisture continues to build up in the oil, reducing the effectiveness of the lubrication system.
The negative effect of short-trip driving on engine life cannot be minimized. A car driven often on long freeway trips can easily have double or triple the life of a car used almost exclusively for short hops.
So, your father-in-law’s idea is to get the engine to heat up more quickly and get hotter, in an effort to burn off the moisture.
You are absolutely right that the blanket is a fire hazard, since it no doubt gets saturated with grease and oil and could catch fire if it came in contact with the hot exhaust manifold. Also, I’m not sure it would really work, since the cooling system is going to regulate the engine temperature and prevent it from getting any hotter than it was designed to get.
A better alternative would be to get frequent oil changes, perhaps every three months regardless of the mileage, and periodically take the car out for half an hour drives at freeway speeds.
* Vartabedian cannot answer mail personally but will attempt to respond in this column to automotive questions of general interest. Do not telephone. Write to Your Wheels, 1875 I Street NW, Suite 1100, Washington, D.C. 20006.