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AUGUST 2010

Q: What is a cabin air filter? And if mine still looks clean, does it need to be replaced?
A: : Automotive technology has changed dramatically in recent years, as automakers respond to new regulations and consumer demands. As a result, many vehicles are now equipped with a cabin air filter (or "pollen filter") to improve the air you breathe when you're inside your vehicle.

Most European vehicles have been equipped with cabin air filters since the early '90s, but these early filter designs - little more than a piece of mesh fabric - were largely ineffective. In contrast, today's filters are scientific masterpieces, electrostatically charged to attract airborne particles and trap them until the filter is replaced. These filters can remove a significant amount of dust and still allow adequate airflow to keep you and your passengers comfortable.

Activated charcoal is another feature often built into modern cabin air filters. Charcoal absorbs pollutants, both from your own vehicle and those driving ahead of you on the highway, so you and your passengers won't have to breathe them in. If you've ever had an aquarium, you're familiar with how the charcoal filter absorbs pollutants so the fish have clean water in which to live - your vehicle's filter operates on the same principle!

Replacement of your cabin air filter at the specified interval is important, even if the filter looks clean. The electrostatic charge and the activated charcoal both become depleted over time - a condition that is invisible to the naked eye, yet renders the filter less and less effective. Have your filter replaced regularly, and breathe easy!

JULY 2010

Q: Should I have an expensive repair performed on my vehicle, or just "dump it" and get another vehicle?
A: : From time-to-time a client facing a large repair bill will ask me this when they are trying to decide if their vehicle is "worth it".

Some might think that as a repair-shop owner my answer is always that the repairs be performed (after all, that is how we earn our living). But, I like to sleep soundly at night and have given this question much thought. Here is my standard answer.

If someone doesn't like their vehicle (repaired or not) then they will probably like it less after pouring money into it. In addition, repairs will only maintain a car's value not increase it, so it may be that the repair money would be better used toward a car that the owner will be happy with.

On the "other side of the coin" Mercedes-Benz owners typically keep their vehicles an average of about 10 times longer than the average vehicle owner. By doing so the Mercedes-Benz owner is able to spread out the repair cost over years and maybe even decades of vehicle ownership. When this is taken into consideration the repair cost is almost always going to be the more cost-effective choice.

Let's look at a specific example. Let's use a 1995 E-Class that needs a transmission replacement and the client is considering purchasing a 2005 (ten-years newer) E-Class as replacement.

Here is how it pencils out:

• Value of current vehicle with transmission: $5000
• Depreciation of vehicle over next two years: $500
• Cost of transmission: $4000
• Repair cost factored over two years: Less than $170 per month
• Value of vehicle without repair performed: $500
• OR
• Cost of comparable replacement vehicle: $25,000
• Depreciation of replacement vehicle over two years: $5000
• Increased insurance premiums over two years: $1200

In two years you will have spent the $4000 (plus maintenance costs) on the vehicle needing the large repair. In two years you will have spent $26,200 (plus maintenance costs) on the replacement vehicle. The replacement vehicle depreciated $5000 while the repaired vehicle may have depreciated only $500. There may also be financing charges associated with the replacement vehicle.

The "least expensive" vehicle you will ever own is the one you currently own. So you will want to carefully consider whether or not replacement is better than repairing.

JUNE 2010

Q: I am considering purchasing a used vehicle. What should I do?
A: The used vehicle market has fluctuated dramatically during the last two years. Guidelines for purchasing a "previously owned" vehicle have remained consistent in some regards, and drastically changed in others.

When deciding if a vehicle will fit your needs, the guidelines remain the same. Choose a model of vehicle that will fit your daily use needs. If you have 5 persons in your household which rely on you for transportation, a SL500 might not be the best fit for you at this time (but sure may be tempting!). Likewise, a person whom frequently takes solo highway trips may benefit from the features and aerodynamics of a SL500.

Once you have selected a particular model there is still work to be done. I suggest you spend some time driving the particular model. This can be easier to do than it may sound. If the model you are considering is still being produced, most car rental agencies can rent you a similar vehicle for a weekend at fairly modest cost. If the model you are considering is out of production you still have options. Check local advertisements for vehicles like the one you desire. Contact some of the sellers and arrange to view and drive their vehicles. A private party may be more inclined to allow you to drive the vehicle 20-30 miles than a retail dealership would. There are many local dealers that will allow this long of a test drive, but may require you to sign a "borrowed car agreement" and credit application before you take the vehicle.

Now that you have "borrowed" a vehicle from a seller, take the vehicle to your residence. Does the vehicle fit where you intend to park it? Now drive your daily route. Park the vehicle at your grocery store, church, school, and place of business -- anywhere you frequent. Between these destinations you can observe how the vehicle operates within your daily life. Take a note pad with you and notate any questions you have along the way (what to do with these questions is addressed later). Avoid taking too many people with you, as this may distract you from the vehicle and how it operates in real life. Most likely you do not drive down the road opening and closing all the windows, sunroof, glove box, and sun visors at the same time. Then again, maybe your regular passengers do!

Now you know the vehicle model you wish to purchase and can determine the market value of similar vehicles. You have completed your homework. Now it is time to select the vehicle that catches your eye. But wait! Do not agree on the price and hand over your money just yet. There is one more step in the process of buying a pre-owned vehicle. Schedule an acceptable date for a pre-purchase inspection to be performed. You will have to coordinate with your favorite automotive technician and the vehicle seller. Depending on the price of the vehicle you are purchasing, I would suggest a minimum of a one hour inspection be performed. A vehicle being sold for $20,000.00 or upwards should have at least a two hour inspection by a professional technician. Remember the note pad mentioned above? This is when you pull out your notes and present them to your technician. They should be able to answer the questions you have noted. The vehicle seller may not be able to answer your questions about the vehicle, but your technician should. Your technician should also be able to provide you itemized cost estimates for any defects.

Now the time has come for actually buying the vehicle. To summarize what you have done to this point: Driven the vehicle extensively while making notes, determined the fair market price of similar vehicles, had the vehicle professionally inspected and questions answered. You have collected all this information to prepare yourself for "The Sale Negotiation".

The sale negotiation does not have to be a stressful life experience. You have done your homework and know the condition of the vehicle and what it is worth. My recommendation is to enter negotiations from this perspective. If your repair technician provided you estimates that total less than one-thousand dollars, consider these needed repairs as normal and not a factor in the price negotiation. Any expected repair costs above one-thousand dollars I believe should be reflected in the agreed sale price of the vehicle. To clarify, if the fair market value of the vehicle (based on your research) is $18,000.00 and the technician you hire to perform the pre-purchase inspection gives you repair estimates that total two-thousand dollars, then I feel it is reasonable to expect the seller to reduce the sale price of the vehicle by one-thousand. You may be wondering, "why disregard the first one-thousand dollars of needed repairs?". Well, you are purchasing a used vehicle, not a new vehicle. You should not expect a used vehicle to be 100% like new in condition. Likewise, most sellers would not want to invest one-thousand dollars in a vehicle they will not longer have the use of. However, repairs exceeding one-thousand dollars, I consider to be excessive and should be addressed prior to selling the vehicle.

This all may sound like a large amount of work. But you did ask how I would go about purchasing a pre-owned vehicle. Remember, in the State of California all private party used vehicle sales are "as-is" and do not include a warranty or cooling-off period. Once you have paid for the vehicle, signed the bill of sale, and received the title - you are the owner.

MAY 2010

Q: Does my Mercedes-Benz have a timing belt that needs to be replaced?
A: I have never seen a Mercedes-Benz engine with a timing belt. I'm sure someone can show me one, but I have never come across one in all my years as an automotive technician in San Luis Obispo County. However, every Mercedes-Benz engine I have worked on is equipped with a timing chain. What's the difference? A timing chain is made of hardened metal and is an internally lubricated part of the engine, while a timing belt is usually made of rubber and is located beneath a plastic cover.

In our experience at Star Automotive, we have found that a timing chain can stretch over time as it labors within the engine. If it's allowed to stretch too far, the timing chain can "jump" and cause serious damage to the engine valves.

What to do? We have created some "rule of thumb" guidelines - not official Mercedes-Benz information, just helpful advice for those considering replacement of the timing chain.

For vehicles manufactured in 1997 and earlier, we recommend replacement every 100,000 miles. If replacement is performed after 100,000 miles, we recommend that the chain guides be replaced at the same time. We do make an exception for V-8 models from the 1980s (380, 420, 500 and 560 models), and recommend that the upper chain guides be replaced every time the timing chain is replaced.

Vehicles manufactured after 1997 feature a timing chain design that has proven to be much more durable, lasting well over 150,000 miles without failure. I believe we will eventually recommend replacing the timing chains on these vehicles every 200,000 miles, with the exception of models with 4-cylinder engines (220 and 230). As these engines were designed for fuel economy, their timing chains are much lighter in weight. While we have not seen routine failures, we still recommend replacing the timing chain every 100,000 miles in these vehicles, rather than risk a failure and find yourself with a much more expensive engine repair.

APRIL 2010

Q: I encounter lots of advertisements for fuel additives. Should I be using one?
A: You could ask this question of 10 automotive technicians and get 10 different answers! As for me, I'll answer by sticking to the facts as they apply to Mercedes-Benz gasoline powered vehicles. (There are special fuel guidelines for Mercedes-Benz diesel powered vehicles, so if you drive one, please check your owner's manual for information on approved fuel additives and proper usage.)

Mercedes-Benz has shared its position on fuel additives with automotive technicians (via a 1990 bulletin titled "Fuel Additives for Mercedes-Benz Engines") as well as consumers (via owners' manuals for most vehicles manufactured since that year).

In short, their position is: Fuel additives can cause too high a concentration of chemicals within the fuel supply, and these chemicals can affect engine performance and cause engine damage.

You may be wondering, "How can one little bottle create too high a concentration?" The answer may surprise you. Virtually all gasoline sold in the U.S. already contains a fuel additive, right out of the pump! Mixing a bottled additive into fuel that already contains an additive can, indeed, result in a high chemical concentration.

Do different fuel brands contain different additives? Again, the answer may surprise you. I have an uncle and a cousin who have worked in fuel refineries. (And no, I don't get a family discount on gasoline!) They both confirmed that there are only a handful of refineries operating in the U.S., and the fuel produced by one refinery is commonly sold at hundreds of different stations under many different brand names all with the same additive.

So the short answer to the question, "Should I be using a fuel additive?" is no. There is no reason to double-up on what the fuel already contains.

MARCH 2010

Q: When I turn the key to start my vehicle, nothing happens. I think the battery is dead. What should I do?
A: Most drivers are familiar with the practice of "jump starting" a vehicle. While the jump starting procedure is covered in most owners' manuals, what is not covered is the damage that can result from jump starting. Now, I don't intend to replace the manufacturer's information in your owner's manual, but I would like to tell you how we perform the process at Star Automotive based on our 32 years of combined auto repair experience.

Most vehicles manufactured since the late 1970s have an on-board computer. In fact, late model Mercedes-Benz vehicles have over 20 computers, and some models have as many as 50! Most automotive computers are designed to operate reliably with a supply voltage between 10 and 14.5 volts. When another vehicle is connected to your "dead" vehicle, you run the risk of a "voltage spike" during which the voltage momentarily jumps above 14.5 volts. Even though the spike lasts only a fraction of a second, that's more than long enough to damage a computer. The result can be costly, sometimes running into thousands of dollars' worth of supplemental repairs.

We have determined that the safest way to jump start a dead battery is to connect it to another battery rather than another vehicle. Most auto parts stores sell "jump boxes" which basically consist of a battery and jumper cables in a single unit. Likewise, most reputable repair shops and towing companies have a jump box in their tool supply. Of course, using another battery to jump start your vehicle is no guarantee of avoiding damage, but it is certainly safer than connecting to another vehicle. Once the engine is started, it is advisable to wait 4-5 minutes before disconnecting the jump box or second battery.

On the subject of batteries, Star Automotive sells factory Mercedes-Benz batteries because we've found them to be the only batteries that fit the application properly and allow the venting hoses to be attached correctly. (All liquid-acid batteries emit harmful gases that should be vented outside of the vehicle.) If you have questions about your battery, please call or stop by Star Automotive - we'd be happy to help.