Oil Change Services...Frequently Asked Questions
- Why Change Motor Oil?
- Why Change Oil Filters?
- How Often Should Oil Be Changed?
- Why the Time Recommendation?
- What Really Causes Sludge in Oil?
- Size of a Filter
- What About Differential Gearbox Services?
- Fuel Filter Replacement - How does it affect fuel efficiency?
- PCV Valves - What Are They and When Should You Service?
- What Are Your Inspection and Replacement Policies for Air Filters?
- Do You Replace Wiper Blades?
Why Change Motor Oil?
The additive package is consumed, used up or destroyed as the engine operates. When the additive package is destroyed, it becomes a contaminant; it doesn't just evaporate or disappear. If it is not removed at good service intervals, it could possibly become a catalyst to sludge formation. For instance, the viscosity index improver is shaped like an expanding and contracting slinky-toy. When it is destroyed, the sheared parts are useless and become contamination to be caught in the oil filter.
Motor oil in the engine becomes contaminated with many things including blow-by, condensation, fuel, dust, metallic shavings, and sometimes even antifreeze. The contaminant, especially those that are liquid, are not completely removed by the oil filter. As they are whipped into the oil, sludge is formed. This sludge, if not removed by changing the oil, may eventually be baked onto various parts of the engine. Baked-on or oxidized sludge can cause the engine to perform less efficiently and may eventually lead to engine failure.Back to Top
Why Change Oil Filters
The oil filer's primary function is to "sift" or remove oil contaminants. The filter allows oil to flow through while restricting solid contaminants, preventing them from re-entering the engine lubricating areas. When the oil filter element becomes full or "clogged", the oil and contaminants flow around the filter element. This is called "by-passing." When by-passing occurs, contaminants return to the engine, possibly causing damage to moving parts, accelerating sludge formation.Back to Top
How Often Should Oil be Changed?
"Normal" vs. "Severe" Driving Conditions Upon reviewing most owner's manuals, you will find that almost all list oil-change recommendations for what is considered "normal" operation and for "severe service" conditions. What many fail to do is to define what is meant by "normal," or what the American Petroleum Institute (API) identifies as "ideal." However, the service manuals will not define "severe service." Thus, you may be left with the understanding that anything which is not "severe service" must be "normal." Actually, there are very few driving conditions that can be classified as "normal" or "ideal."
API defines automotive engine operation as "ideal" when a car is moving at highway speeds on a paved road in a dust-free environment.
Today, almost all driving is done under "severe service" conditions. The American Petroleum Institute defines "severe service" as follows:
- Trips less than 10 miles (16.09 kilometers)
- Driving in dust and sand
- Cold weather that prevents full engine warmup
- Idling for extended periods
- Stop-and-go driving
- Pulling trailers
- Heavy loads
- Operating in any other heavy-duty and severe service, such as sustained high-speed driving in hot weather.
For "severe" service, most owner's manuals recommend an oil change every 3,000 miles or 90 days and an oil filter change with every oil change. Severe service operations represent the type of driving done by most motorists.Back to Top
Why the Time Recommendation?
Even though an engine isn't running, heat and cooling from sitting still attracts moisture into the crankcase. Moisture is acidic. If the engine isn't run long enough to boil off this accumulated moisture, the acid compounds become damaging. So, the oil may need to be changed at this time, rather than the mileage interval. Again, follow your vehicle manufactures's recommendation.Back to Top
What Really Causes Sludge in Oil?
Sludge formation has nothing to do with the original base stocks used to formulate the oil. The causes of sludge formation are:
- When oil isn't changed frequently enough, oil is eventually whipped together with contaminants and it bakes (oxidizes).
- Contamination (blow-by, condensation, fuel, dust, metallic shavings, antifreeze) mixed into the oil. Example: during a routine valve cover gasket replacement, antifreeze could accidentally run or drip into the oil, creating large amounts of sludge very rapidly.
Size of a Filter
The effectiveness of a filter over time is directly related to its size. The trend in passenger vehicle oil filter construction over the last 10 years as been to downsize. Up and through the 1980's, most auto and light truck filters held approximately a quart of oil. The downsizing of the 1990's has led to filters which now barely hold a half a quart of oil.
On the industrial side, 18-wheeler diesels have gone from utilizing a filter which contains one and a half quarts of oil, to one which holds three quarts of oil, and some are utilizing parallel filter mountings to carry two filters which hold a gallon and a half of oil. It appears that the industrial market understands physics principles better than the automotive and light truck market.
Only so much contamination will fit into an oil filter and then it bypasses. Neither modern oils nor oil filters address the issue of stopping blow-by contamination at the piston rings. Until the blow-by contamination is addressed, oil will continue to become contaminated, and filters will continue to clog, at the same rates.Back to Top
What About Differential Gearbox Services?
Most of us grew up believing that differential gearbox fluid was something to be checked and topped off, but not changed. Depending on the make and model of the automobile and its usage, automobile manufacturers generally recommend that differential fluid be completely replaced at intervals from 12,000 to 48,000 miles.
Vehicles used for towing (even occasionally) and some models with limited-slip differentials require service every 12,000 miles. In today's sophisticated market, the average automobile probably needs this service about 24,000 to 30,000 miles.Back to Top
Fuel Filter Replacement - How does it affect fuel efficiency?
Every time a vehicle’s driver presses the gas pedal, he is controlling how much air and fuel enters the engine. The air filter helps keep debris from entering the engine and a fuel filter helps protect the fuel system.
The fuel from the fuel tank is typically pumped from a pump inside the fuel tank to the engine. In the line between the fuel tank and the engine, a fuel filter is typically present to help protect the fuel system. As a fuel filter slowly becomes clogged, the restricted fuel flow could lead to poor acceleration and reduced engine performance as well as other issues.Back to Top
PCV Valves - What Are They and When Should You Service?
The Positive Crankcase Ventilation (PCV) system is a controlled vacuum leak system. Its basic function is to vent the crankcase fumes back into the carburetor to burn off. It also removes moisture and sludge from the engine at the same time.
Proper maintenance of the PCV valve should be a top priority for any car owner.
A PCV valve must be clean to operate efficiently. A clogged or sticky valve creates deposit buildup and increases internal pressure. This results in blocked pump screens and passages that inhibit proper engine lubrication. A clogged PCV system can cause oil contamination, increased oil consumption and lower gas mileage.
Automotive manufacturers recommend inspecting and/or replacing the PCV valve every 12,000 to 24,000 miles or once a year. For maximum engine performance, it is a good idea to change the breather element then, also.Back to Top
What Are Your Inspection and Replacement Policies for Air Filters?
Automotive air filters have always required periodic maintenance. An automotive engine runs much smoother when the air filter is clean. If the filter is wet, damaged, or dirty, it should be replaced with a new one designed specifically for your engine.
Running your car with a clogged filter could result in hard stalling, stalling and poor gas mileage. An air filter may become clogged or loaded with contaminate quicker, depending on the nature of the area where the vehicle is driven, such as dusty conditions. A damaged filter can cause the engine to have excessive wear.
The most common way to determine if a new filter is needed is by a visual check and judgment call. We inspect your air filter at every oil change. Our recommendation guide is that the air filter be changed every third oil change or 10,000 to 12,000 miles. This, of course, after inspection by our service technician and you our guest.Back to Top
Do You Replace Wiper Blades?
Cityview Car Wash and Oil Change can install complete wiper blade and arm sets while we service your vehicle. Ask any of our technicians for price information.Back to Top
Carwash Hours: Mon-Sat 8AM to 7PM, Sun 9AM to 5PM
Lube Hours: Mon-Sat 8AM to 6PM, Sun 9AM to 5PM
4665 Bryant Irvin Road, Fort Worth, Texas 76132