THE GOODS : Warm-Ups Are Now Just a Practice of the Past
Question: Friends living on both sides of me drive late-model cars. I have noticed that whenever they start their engines, even on very cold days, they take off down the street at a good clip the moment the engine starts. I always warm up my cars and take off slowly. Even with 100,000 miles, I have never had a car that burned oil, even though I change my oil only once a year. Am I right?
--H.S.
Answer: It’s always hard to argue with success, but every expert will say that you are wrong on both counts.
New oils contain additives, so-called pour-point depressants, that allow them to flow at very low temperatures and provide very good lubrication to cold moving parts.
Auto makers have been recommending for years that owners use 5W-30 oils, which at low temperatures are thin and quickly rise to the correct pressure inside an engine’s narrow passageways. New friction modifiers make these lubricants better than ever.
The problem with older 10W-30 oil was that its consistency was so thick at low temperatures that it would barely flow and very small volumes of oil would actually reach moving parts in a cold engine.
As a result of improvements in oil, the whole concept of warming up a car is widely regarded as passe. Few owners manuals suggest any warm-up period, and experts, such as Valvoline’s Norm Hudecki, recommend only enough warm-up for the engine speed to stabilize--typically a few seconds. Still, it’s hard to kill old habits and perhaps warming up an engine allows the new oils to do an even better job.
But experts would fault your oil-change routine. You ought to change your oil every 3,000 miles or every six months.
By going a year between changes, you risk contaminating the oil with sludge, water condensation and possibly acid. Although the petroleum itself stays healthy, the additives in the oil are subject to breakdown, particularly the chains of molecules that control the viscosity of the oil.
Another problem with long intervals between oil changes is that if you don’t drive much, the engine can build up water condensation. After a while, sulfur gases that escape from the engine’s combustion chambers combine with the condensation in the crankcase to form sulfuric acid, a nasty corrosive to engine parts.
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Q: I have about $3,000 to spend on a car for my son at college. What would you suggest?
--M.G.
A: Young men have a high fatal accident rate, so I would opt for the safest possible vehicle and worry about reliability second.
With $3,000, you are not going to find a late-model car equipped with air bags, so I would look for a full-size car that offers far better protection than a compact. Operating and repair costs will be higher, but the safety factor is important for a teen-ager.
