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A letter from Stew


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Newsletter No 40
February 2004


Well, we all survived last year – whew!  I am very thankful that I have a business with such thoughtful and wonderful people as clients.  Frankly, it makes it all worthwhile.

I know that we have been somewhat harried and not quite as focused as normal – we expected that to happen with a newborn in the mix.  What came as such a wonderful surprise was the tremendous support we got from you.  How can we thank you for:  baby clothes, baby accessories such as swings, thoughtful advice and most of all patience when we were a little slow returning a call or getting to the phone.


With this cold weather, it’s definitely time for a discussion of winter issues.

I was listening to a Click and Clack episode the other week, and a caller was wondering what could be wrong with her car.  She took a little trip out of town and burned through a tank full of gas in almost half the normal number of miles.  She was afraid something was terribly wrong, but it “seemed to run fine”.  The answers they gave were pretty good.  (It seems that they are either completely right or completely wrong with their answers.)  First,  they asked her what part of the country she was in, and how cold it was when she took the trip.  As it turned out, the weather was pretty cold.

Many people don’t realize how much their fuel economy will drop when the temperatures drop.  My unofficial guide is this:   you will see a big change at temperatures below freezing, another big drop below zero, and another big step down around fifteen to twenty below.


One of the reasons for the drop in fuel economy is that the mineral oils and greases in the chassis and drive train become really sticky in the cold weather.  I know that when pushing “dead” cars into the shop,  they become unmovable (except with another vehicle) when the temperature is below minus fifteen.

A car averaging thirty mpg in the summer may drop into the low twenties for most of the winter and down to fifteen mpg during really cold spells.  Yup, that’s right, just half of the normal mpg.

If your car gets better mileage than this,  you are doing well.  One reason can be that the manufacturers are using more synthetic (i.e., non-mineral) oils and greases in building the cars.  These help a vehicle roll more easily.

Synthetic fluids are significantly more expensive than mineral fluids, and they can add significantly to the cost of maintenance.  No gain without a pain, right? 

What about using synthetic oil in the engine?   There are good reasons and bad reasons for doing this.  Bad reasons first.
Synthetics cost more, and that’s really their only flaw.

 If you want to use synthetic in the engine and expect to recover the added cost of the oil by getting better fuel economy, it is just not going to happen.    If you think your engine will last significantly longer, that’s not going to happen either.  A well-maintained modern engine is capable of 200,000 miles without the use of synthetic engine oil. 

However, there are some very good reasons for switching to synthetic oil .

Synthetic oil  is very pure, and does not  pick up and hold moisture as easily as a regular oil.   Moisture and impurities in regular oils are why you need to change the oil every four months, regardless of the miles accumulated.  The engine corrodes from the inside out if you don’t change regular oil often enough.

Low mileage drivers,  take note! You should be using synthetic oil and changing it based on mileage alone.  I use synthetic oil in my classic cars that get driven very little every year.

The second quality of note of synthetic oils is, as discussed earlier, that they do not thicken up as much when cold.  This doesn’t do much for you until the temperatures  get really cold.  If, for example, you have a cabin on the Gunflint Trail where it can easily get to thirty or forty below, the synthetic will make a difference when you try to start your car.

 So these are the two scenarios where changing to synthetic engine oil is beneficial and cost-effective:  very low annual mileage and extreme cold conditions.


Now back to the Tappet Brothers.  Another question they asked the caller was whether she had checked the tire pressures before she took off on her trip.  Okay,  I would like a show of hands of everyone whose tires have been checked within the last week.  You get the Good Car Owner Award if you answer yes! 

Tires can create a significant amount of drag.  The higher the pressure in the tire, the lower the drag. When the pressure gets below twenty psi, the drag increases enormously. And this is going to decrease fuel economy.

Low tire pressure can lead to blowouts, and if you have a top-heavy car like an SUV, it can cause a roll over.  Low pressure makes the tire more vulnerable to damage from objects or potholes in the road, too.

So, if high pressure is so good, why not pump them up to fifty or so?  Every tire made has a maximum inflation pressure molded into the side.  You should never exceed this pressure (when checked cold, before driving).  Most passenger car tires are 36 psi maximum, with an increasing number of the so-called low rolling resistance tires having a maximum of 44 psi. 

So, your tires were checked a month ago, and they never lose air.  Why should you check them again so soon?

Tire pressures can become dangerously low simply with temperature changes.  As the temperatures drop, the pressures drop.  This is known as Boyle’s Law.  (And you thought your high school and college chemistry classes weren’t relevant!)  In the fall and early winter, we see a surge of tire problems.

So what else did Click and Clack have to say?  Well, not too much more that was really relevant.  Wind was mentioned as a  factor in fuel consumption, and indeed it is.  What they didn’t mention is the density of the air, which is probably as significant as some of the wind factors; but let’s move on, shall we?


Another “hot” winter issue I get asked about is whether to let the car warm up before driving.  Is it a good thing or a bad thing?  Well, that depends.  The manufacturers universally say DON’T DO IT.  Those of us living in very cold climates universally DO IT anyway.  Who is right?

Here are some things to think about. An unattended running car can do something bad, like start a fire or self-destruct.  Rarely, but I have seen it more than once.  Never run a car unattended in a garage or other enclosure (fire hazard and a carbon monoxide hazard, too). 

If a car has been sitting outside and is cooler than the surrounding air, driving before the heater is working can be a safety hazard.  Your windows can suddenly fog or frost on the outside, and blind you.  This is especially true in spring and fall with temperatures around freezing.

If you pull out onto a sloppy road and get a load of slush on your cold windshield, your wipers will have a hard time without a little warmth from the heater and the interior. 

And, some cars are just hard to drive until they get a bit warm.  This is especially a problem with manual transmissions that won’t shift properly until warm.  If this is very apparent with your car, it may be that the oil in the transmission is too old or the incorrect type.  This is a very easily fixed problem.

In summary, try to minimize the time your car is idling. Cars were not designed to be rolling saunas.  Don’t go to the other extreme though.  We have all seen the guy who was in such a hurry that he scraped out just a small porthole in the ice on the windshield before blindly driving away.


Last fall’s newsletter article about the Prius  generated more interest than I could possibly have imagined.  With our information and encouragement, at least three people have purchased or ordered new Priuses.  This makes me happy.  (I only wish I got a commission from Toyota…)  Toyota has seen a level of demand for the cars that they cannot possibly meet, so they’re ramping up production.  Maybe the other automakers will take notice and reenergize (or energize)  their hybrid programs.

With our driving habits remaining the same, we saw a significant drop in our fuel economy as winter blew in.  Summer averages for a tank were a little over fifty mpg.  As the temperatures fell below freezing, we slipped into the forties.  The very short spell of below zero temps put the meter on the thirty-eight and thirty-nine mpg marks.  It has gone up into the forties again since then.


We are now selling miniature battery chargers known as “Battery Tenders”.  These are designed for low mileage cars, or cars that don’t necessarily get driven every day.

What these devices do is keep a full charge in the battery.  We install the leads into the battery, and when you park the car in the garage, you plug the device into an electrical outlet.

No more getting home from a great vacation only to discover a dead car!

If you’re interested, give us a call.

Hope to hear from you soon.

Stop in to visit us, or if you have any questions about your cars, call us at 651-635-0395.


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