About Us RX Automotive

Rx Automotive | Complete Auto Repair

For years, RX Automotive has been a trusted name in St. Charles auto repair, known for reliable service, ASE-certified technicians, and customer-first care.


In 2025, RX Automotive proudly joined the Diehl Auto Repair family, combining two locally trusted companies into one stronger network of auto repair shops. With Diehl’s growth from one location in 2016 to five locations today, this partnership means RX customers now have access to even more convenient locations, expanded services, and fleet repair capabilities—all while keeping the same friendly team and high-quality service they’ve always relied on.


As part of Diehl Auto Repair, RX Automotive continues to offer brake service, diagnostics, oil changes, tires, engine repair, and scheduled maintenance, all backed by warranty and performed with integrity.


We’re excited to keep serving St. Charles and beyond with the same local auto repair expertise, now strengthened by the Diehl Auto Repair network.

RX Automotive — Now proudly part of Diehl Auto Repair.

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By Les Santeler August 5, 2025
We would like to give you an update on some of the things happening in automotive fluids. You know, cars are becoming more sophisticated everyday – and fluids such as, oil, coolant and transmission fluid are becoming more specialized at about the same pace. The do-it-yourselfer has to be pretty careful so that they do not actually harm their vehicle with the wrong type of fluid. That is why so many IL car owners rely on the advice of their service consultant to not only get the correct family of fluids, but to suggest the formulation that is best for their car and the way they drive. Let’s start with engine oil. If you have been paying attention, you will have noticed a number of new oil weights on the scene in the last several years. Modern engines are built to much tighter tolerances and have very complicated valve trains. The oil must be thin enough to lubricate complicated parts when the engine is cold. The weight of an oil is expressed in terms like 20-W-50 or 5-W-30. Manufacturers recommend the weight of oil for each vehicle they make. The recommendation is based on engine design. Your Saint Charles service center will know what weight your manufacturer recommends – and it’s important to follow those recommendations. A service adviser at Rx Automotive can also offer suggestions for special formulations and can explain conventional and synthetic oils. Antifreeze, or engine coolant, is another area that has become more complicated. For a long time, manufacturers only called for a couple of different types of coolant. Now there are several different formulations that are needed because of the different materials that manufacturers are using to build the cooling system. Using the wrong type of coolant can actually void your warranty, so you want to get that right. Transmission fluid is beginning to be specialized as well. New transmission designs have particular requirements that mandate the use of specific formulations. Recently, new, somewhat confusing, standards for brake fluid have also been released. Not too long ago, there was a good chance that all of the vehicles at your house would use many of the same fluids. However, as automotive technology advances, the array of basic automotive fluids you need will grow. And, some of the formulations will cost a little more. Fortunately, your Bartlett service center will continue to update their training to keep pace with technology so that you’ll get the right fluids your car needs. It’s all part of the commitment your service center makes to your driving peace of mind.
By Les Santeler August 5, 2025
The last new car sold with a carburetor in North America rolled out of the dealership in 1990. Since then, all new vehicles have had fuel injectors. In very simple terms, a fuel injector is a valve that squirts fuel into your engine. Your engine control computer tells the fuel injector how much gas to deliver as well as the precise time it should be delivered. Of course this happens thousands of times a minute. Fuel injection is a much more precise way of delivering fuel than carburetors. That translates into better fuel economy and power. Virtually all fuel injectors for gas engines are known as port fuel injectors because they deliver the fuel to a port just outside the cylinder. Port fuel injectors operate at about 40 to 80 pounds per square inch of pressure. A few auto makers have introduced gas direct injection systems on some engines recently. These systems inject the gas directly into the cylinders under very high pressure – hundreds of times the pressure of port injection systems. Although more complicated, direct injection technology promises greater power with improved fuel economy, so we can expect to see more of it in the future. As you can see, the level of precision required of your fuel injectors is very high. They need to be operating properly in order for your car to run right. High temperatures under your hood and variations in gas quality cause fuel injectors to become fouled with wax, dirt, and carbon. Injectors can become partially clogged, preventing them from delivering the proper amount of fuel at the correct pressure. The design of each engine requires a specific spray pattern from the fuel injector that might be altered when the injector is dirty. When injectors are dirty, the fuel doesn’t burn as efficiently resulting in poor fuel economy and loss of power. So it is important to keep your fuel injectors clean. Skilled service technicians at Rx Automotive in Saint Charles can perform a fuel system service for you. (Visit http://lessanteler.autovideotipsblog.com/contact-us/.) That is a fuel system service – not just fuel injector cleaning. That is because the fuel has a lot of ways to become dirty or contaminated between the gas tank and the fuel injector. A fuel system service starts with a fuel filter replacement. This filter cleans the gas as it leaves the tank. The various parts of the fuel intake system need to be cleaned from time to time to remove harmful gum, deposits and varnish. Finally, the fuel injectors are cleaned so that they operate properly and deliver the right amount of fuel at the right time. Your Elburn area service center uses a process for cleaning your fuel system that includes state-of-the-art cleaning chemicals as well as some old fashioned scrubbing. Proper maintenance of your fuel system means that you will spend less on gas, enjoy strong performance and prevent costly repairs down the road.
By Les Santeler August 5, 2025
Here at AutoNetTV , we have viewers, like you, from all across the country who write to us with questions or feedback. One common question we’re asked is: What is a differential and what does it do? You may have been told your differential needs service, or seen it as an option up on the service menu. Differential service covers a lot of things, so let’s first talk about what a differential does. As you drive through a turn, your outside wheels and inside wheels turn at different speeds. Kind of like the cars going around a race track – the ones driving in the outside lanes have a greater distance to travel than the cars in the inside lanes. The differential is what allows the outside and inside drive wheels to rotate at slightly different speeds so that the tires don’t hop or skip while taking corners, or lose traction in dirt or snow. Differentials have gears in them that transfer the power from the drive train to your wheels – which is why they’re often referred to as gear boxes. The gears need to be very strong to do this work, and they need to be properly protected so that they’ll last. All vehicles have some form of differential. If you have a front-wheel drive car, your differential is often called a transaxle and is located in the front. If you have rear-wheel drive, the differential is in the back of the car. If you have a four-wheel drive vehicle, you will have a differential in the front and the back – and in the middle as well. The center differential adjusts for differences in speed between the front and rear wheels. Differential fluid lubricates and cools the gears. Over time, the fluid can get dirty from bits of the gears grinding off. The additives that keep the fluid clean and protect the differential break down over time. So your vehicle manufacturer has scheduled intervals for you to have your differential fluid changed. Differentials are hard working mechanisms, and, along with the gears in a manual transmission, need to be serviced regularly with high-quality, replacement fluid. Your Bartlett automotive service advisor can give you more information as to when your next differential service is recommended. You can also ask if they have a record of when the service was last completed.  As with most service intervals, if you are driving under more severe conditions, you will want to service your differential more frequently. “Severe service” conditions are defined in most owners’ manuals, and include: frequent starts and stops, short trips, cold weather, hot weather and towing. All these conditions add to the stress of the vehicle and its parts. Also, off-roading in IL can be especially hard on differentials, especially if you cross streams. Proper service will extend the life of your gears and keep them running more smoothly. If you have never had your differential checked, visit http://lessanteler.autovideotipsblog.com/contact-us/ for more information.
By Les Santeler August 5, 2025
What type of technology do you use? Do you prefer an 8-track tape or an iPod? When it comes to winter tires, much of the public’s perception dates back to when 8-track was the best way to listen to the Bee Gees. Twenty years ago, winter tires differed from highway tires only in their tread design. We called them snow tires back then and they had big, knobby lugs that were designed to give good traction in deep snow. They had the same rubber compound as regular tires and they weren’t very good on ice, packed snow or wet roads. They were not even very good on dry roads. They really helped in deep or loose snow, but they did a poor job the rest of the time. They were loud and rode hard. You couldn’t wait to get them off in the spring. Then all-season tires started to come along. All-season tires are really a compromise between summer and winter performance. They have acceptable hot weather ride and tread life, and you can get through mild winter road conditions OK. But there are some really good reasons to consider winter tires. Modern winter tires do a terrific job in a wide range of winter conditions. First of all, below 45 degrees Fahrenheit, regular tires become hard and inflexible. That means they don’t provide the road grip you need. Even if you don’t live somewhere with a lot of snow, but it still gets below 45 degrees in the winter, you will be safer with winter tires. In addition, they are specifically designed to more effectively move snow and water. That’s the key to traction on ice, packed snow and wet roads. They use a micro-pore compound that allows the tire to bite into ice and snow. They also use wider grooves that run around the circumference of the tread to expel snow from the tire better. The lugs and grooves on winter tires have a special shape that throws the packed snow out of the tread as the tire turns. The tread is then open when it comes back in contact with the road and can provide good traction. Winter tires also have a lot of sipes. Sipes are thin slits in the tread. The edge of the sipes grab ice and packed snow to provide tons of traction and to expel water and slush out of the tread. winter tires have a rounder casing to cut into the snow’s surface. The treads on regular summer tires can actually get packed with snow instead and become very slick. winter tires offer 25% to 50% more traction than all-season tires. And when it comes to stopping power, all-season tires take 42% longer to stop than winter tires. Sometimes that’s the difference between getting home safely and spending the night in a snow bank. Now back when the 8-track was king, you just put snow tires on the drive wheels. That worked out OK because the rubber compound was essentially the same. Now, winter tires provide so much more traction than all-season or summer tires , that there’s a huge difference between the traction at the front and rear ends of the car if you only put winter tires on the drive wheels. For example: if you take a corner on an icy road and the rear end starts to slide out, essentially the rear is trying to pass the front because it’s going faster. If you have high traction winter tires only on the front, they are going to be much more effective at transferring cornering grip and stopping power to the front wheels. This will actually cause the rear end to whip out even more. That’s why tire manufactures instruct their dealers that they must install winter tires on the rear wheels as well whenever they put winter tires on the front end of any vehicle. It’s a major safety concern. It’s strongly recommended that winter tires be installed on all four wheels on rear wheel drive vehicles as well. The front tires do most of the steering and braking work – it only makes sense that you provide the front end with the best traction you can. People often assume that if they have four-wheel drive or all-wheel drive they don’t need winter tires on all four wheels. Would you intentionally disconnect the four-wheel drive in poor road conditions? Of course you wouldn’t, but that’s essentially what you do if you only put winter tires on one end. It only makes sense to have the same level of traction and control at all four corners. The province of Quebec in Canada has issued a law requiring all passenger vehicles, taxis and rental cars with Quebec license plates to install a full set of four winter tires between November 15th and April 1. It’s that important. Many modern cars have traction control and anti-lock brakes so people may think that they don’t need winter tires. But you need traction to accelerate, steer and stop. The tires provide the traction so that the traction control and anti-lock brakes have something to work with. Look for tires with the symbol of a mountain with a snowflake in it. This means the tire complies with the severe snow standard. All-season tires will have an M&S, for mud and snow, on the sidewall. So when the temperatures drop below 45 degrees, be sure you have a set of four winter tires for maximum performance in snow, packed snow, ice, wet and dry roads. Your tire professional can help you find the right winter tire for your vehicle and driving needs.
By Les Santeler August 5, 2025
When you hear the word ‘ suspension ‘, you may think back to those energetic days of grade school. Well, your car’s suspension is actually a good thing because it keeps your car up off the road and helps provide a comfy ride. It needs to keep your wheels firmly planted over bumps and through curves. Your suspension system has many parts. If you look under your car, it’s basically everything that connects your wheels to the car’s frame. These are heavy duty parts that do a lot of work. They need to be inspected for damage and excessive wear at least once a year. A good time for this is when you get your annual alignment service. Here are some warning signs that your suspension may have problems:
By Les Santeler August 5, 2025
The energy from exploding fuel is what powers your engine. But some of the vapors from the explosions escape into the lower part of the engine, called the crankcase. The crankcase is where your engine oil hangs out. These gases are about 70% unburned fuel. If the gases were allowed to stay in the crankcase, they would quickly contaminate the oil and turn it to sludge. Sludge is one of the biggest enemies of your engine, clogging it up, eventually leading to expensive failures. Also, the pressure build up would cause seals and gaskets to blow out. Therefore, these gases need to be vented out. Gasoline engines used to simply have a hose that let the poisonous fumes vent out into the air. In 1963, the federal government required gas engines to have a special one-way valve installed to help reduce dangerous emissions. Diesel engines are not required to have these valves. The positive crankcase ventilation, or PCV, valve routes crankcase gases through a hose and back into the air intake system where they are re-burned in the engine. Fresh, clean air is brought into the crankcase through a breather tube. It’s really a pretty simple system, but does an important job. The re-circulating air removes moisture and combustion waste from the crankcase, preventing sludge. This extends not only the life of your oil, but the engine as well. The PCV relieves pressure in the crankcase, preventing oil leaks. Eventually, the PCV valve can get gummed up. Then it can not move enough air through the engine to keep it working efficiently. If the PCV valve is sticking enough, you could have oil leaks, excess oil consumption and a fouled intake system. If you experience hesitation or surging or an oil leak, it may be a sign of PCV value problems. Your owners’ manual may give a recommendation for when the PCV valve should be replaced – usually between 20,000 mi/32,000 km and 50,000 mi/80,000 km. Unfortunately, some manufacturers don’t list a recommendation in the manual, so it can be easy to overlook. Many PCV system problems can be diagnosed with a visual inspection. Fortunately, PCV valve replacement is both quick and inexpensive. Proper oil changes will greatly extend the life of the PCV valve. Skipping a few recommended oil changes can allow varnish and gum to build up in the valve, reducing its efficiency. So now when your Saint Charles service technician tells you its time to replace your PCV valve, you will know what he’s talking about. If you have had your car for a while and this is the first you’ve ever heard of a PCV value, ask your tech to check yours out or call Rx Automotive at 630-443-8500.
By Les Santeler August 5, 2025
What is a cabin air filter ?  Is it: A filter for a house in the middle of the woods? A fresh, piney scent? A filter for the passenger compartment of your car? Clever you, it’s 3. A cabin air filter cleans the outside air before it comes into the passenger compartment. It filters out dust, pollen, spores, bacteria, pollutants, sparrows, exhaust gas and odors. These high tech filters can block particles larger than 3 microns. By contrast, a grain of sand is about 200 microns. Now not all vehicles have cabin filters. They are fairly new on the scene. About forty percent of new vehicles come with cabin air filters, but the number is growing every year. Cabin air filters can make for a very nice driving environment. Your car can be a haven during allergy season with very little dust and pollen getting into the cabin. However, the filter eventually gets clogged. When this happens, your heating and air conditioning flow can become restricted. The filter can even get kind of smelly.
By Les Santeler August 5, 2025
Hey Saint Charles, IL Do you hear loud noises under the hood when you turn on your air conditioner ? Do you only get cool air sporadically? If so, it is time to get your air conditioner checked. It’s real easy to take your car’s air conditioner for granted. Just push the right buttons and out comes cool, dry, clean air. But your air conditioning system needs attention from time to time to help it keep its cool. When most people in Saint Charles hear the words “air conditioning problems”, it sends a shiver up their spine. That is because the air conditioning system is fairly complex. It has a lot of parts and when it’s broken, it’s expensive to repair. What things can we do to prevent air conditioning breakdowns? A common cause of air conditioning failure is leaks. Water and air can leak into the system. The system doesn’t work as well with air in it. And water can cause rust that leads to damage of the A/C components. Also, refrigerant, the stuff that makes the air cold, can leak out, reducing the efficiency of the system, making it work harder to cool the air. Periodically evacuating the air conditioning system and recharging it keeps the proper amount of clean refrigerant in the system so it cools better and lasts longer. You should also run the air conditioner regularly, even in a frosty Saint Charles winter, so that it lubricates itself and keeps the seals from drying out, which leads to leaks. Your owner’s manual will have recommendations for how often to service your air conditioner. Of course, if it’s not working right, now is the time to get it checked. Rx Automotive can inspect and test your air conditioning and offer evacuation and recharge services. This goes a long way to avoiding having to bring your air conditioner in for major repairs. New environmental laws have stopped the manufacture of Freon , a refrigerant that was common in cars made before 1993. There is a very limited supply of Freon so the price is very steep. It may not be worth its weight in gold, but it probably is worth its weight in silver. If you have an older vehicle that uses Freon, you may want to consider having it retrofitted to use the new R134-A refrigerant . It will pay for itself in the long run. So, if your AC is just a lot of hot air, bring it in to Rx Automotive for an inspection.
By Les Santeler August 5, 2025
Richard Petty once told AutoNetTV, “You’ve gotta have good brakes. If you’ve got good brakes you can keep yourself out of a lotta trouble.” That’s why a regular brake inspection is on every Saint Charles car’s maintenance schedule. An inspection at Rx Automotive will check your brake system and let you know if there are any problems. Of course, if you’re having trouble with your brakes, get your car into Rx Automotive right away. Here are some symptoms to watch for:

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