Oil Change Services

...Frequently Asked Questions

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.

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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.

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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.

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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.

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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:

  1. When oil isn't changed frequently enough, oil is eventually whipped together with contaminants and it bakes (oxidizes).
  2. 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.
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OPEN 7 DAYS
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

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