Motor Oil Myths & Facts

Everything you need to know about the oil for your car, or truck


Myth #1
  Paraffinic oils cause engine sludge.
Oils from paraffin-based crude are loaded with wax and create engine sludge.
Paraffin base stocks cause sludge.
"x" Brand of motor oil causes sludge, varnish and/or engine deposits.
"Paraffinic" motor oils cause wax-like deposits on the underside of the oil fill cap.

There are two basic types of crude oil, naphthenic and paraffinic. Most conventional engine lubricating oils today are made from paraffinic crude oil. Paraffinic crude oil is recognized for its ability to resist thinning and thickening with temperature, as well as its lubricating properties and resistance to oxidation (sludge forming tendencies). In the refining process, the paraffinic crude oil is broken down into many different products. One of the products is wax, and others are gasoline, kerosene, lubricating oils, asphalt, etc. Virtually every oil marketer uses paraffinic base stocks in blending its engine oil products.

Many people believe the term paraffinic to be synonymous with wax. Some have the misconception that paraffinic oils will coat the engine with a wax film that can result in engine deposits. This is not true. The confusion exists because paraffinic molecules can form wax crystals at low temperatures. In lubricating oils, this wax is removed in a refining process called dewaxing. Wax is a premium product obtained from crude oil, and in order to ensure that we produce the highest quality base stocks available, Quaker State® removes the maximum amount of wax possible during the refining process. The end result is a motor oil product formulated with premium lubricating base oil.

Myth #2
  If the oil turns dark or black quickly, it's no good.
You can tell the condition of oil by the look, smell or color of it.
Dirty (black) motor oil means the oil is breaking down.

A common misconception is that high quality motor oil should come out of an engine looking clean at the time of an oil change. Nothing could be further from the truth. If the oil is doing its job of cleaning the engine, then it should be dirty when it is drained. Motor oil will start looking dirty a short time after it is put to use. In the case of diesel engines, the oil will look dirty within a few hours of operation. These are signs that the motor oil is doing its job of keeping soot, dirt, and other combustion contaminants in suspension to be carried to the filter or removed from the crankcase when the oil is changed. Motor oils have been formulated to hold these contaminants in suspension until they can be removed with an oil and filter change.

Myth #3
  Using synthetic motor oil will void a manufacturer's warranty.

As long as the synthetic product meets the viscosity and performance requirements outlined in the vehicle's owner's manual, using synthetic oil will not interfere with the warranty coverage. However, one exception would be the rotary (Wankel) engine used in certain Mazda vehicles, which recommend against the use of synthetic oil in that particular engine.

Myth #4
  You can't switch from synthetic oil to conventional oil or vice versa.
You need to start with a synthetic blend for a few oil changes before moving to full synthetic oil.
Once you start using synthetic motor oil you cannot go back to conventional oil.
Synthetic and conventional engine oils can't be mixed, or else they react and cause engine problems.

As long as the synthetic motor oil product and conventional motor oil product meet the viscosity and performance requirements outlined in the vehicle's owner's manual, you may interchange them with each other.

Myth #5
  Synthetic oil causes engine leaks.
Synthetic motor oils eat gasket material and cause engines to leak.
Synthetic motor oils affect engine seals and result in excessive oil leakage.
Synthetic oil can't be used on high-mileage engines.
Synthetic and synthetic blend motor oils cannot be used in older or high-mileage vehicles.

Synthetic oils do not cause engine oil leaks. Deteriorated and hardened seals and gasket material cause engine oil leaks. If the seals are already leaking with conventional motor oil, they will leak with synthetic oil. If the seals are in good condition, synthetic oils may be used in high-mileage engines.

Myth #6
  Engines have to be "broken in" before using synthetic oil.
I need to break in my engine with non-detergent oil.
If I use regular oil or synthetic oil in a new engine, my engine will take longer to break in.

It was common years ago for engine manufacturers to recommend non-detergent oils for engine break-in. This was when the pistons used cast-iron "square-faced" rings and the rings needed to wear some to "seat" into the engine. With today's technology of oils and engine manufacturing, engine manufacturers no longer recommend the use of non-detergent oils for the break-in period. In fact, engines today are factory-filled with high quality API SL performance motor oil, which contains high levels of detergents and dispersant additives.

Myth #7
  Synthetic oil lasts longer than conventional oil or extends the oil drain interval.
You can go longer (i.e., 25000 miles) with synthetic oils.
Using synthetic motor oils can double your oil drain interval.
Synthetic motor oils can be used twice as long as conventional motor oils.
Changing only your oil filter every 3000 miles and topping off the oil can extend drain intervals.

We do not recommend extending oil drain intervals beyond the "severe service" maintenance interval of three months or 3,000 miles, whichever comes first. Also, we are unaware of any automobile manufacturer in the United States that currently recognizes using any synthetic oil beyond the recommended oil change intervals outlined in their owner's manual. We emphasize severe service since the majority of motor vehicles are operated in severe driving conditions such as short trips (under 10 miles), dusty or sandy conditions, cold weather, extended idling periods, trailer towing or other harsh conditions. Under ideal conditions, however, such as a dust-free climate, highway driving, light loads, perfect engine performance, etc., the oil drain interval may be extended to the vehicle manufacturer's recommended "normal service" period (generally between 3,000 to 7,500 miles). Contamination by normal wear particles, water, fuel, and other combustion by-products, as well as additive depletion, are the main reasons for changing conventional oils on a regular basis. Synthetic oils are equally susceptible to this problem. The only way to remove these contaminants is to change the oil and filter within manufacturers' recommended intervals.

While it is desirable to change the oil filter before it plugs up because of dirt and contaminant build-up, it is nearly impossible to detect when that condition exists or is about to occur. Regardless of how good an oil filter appears to be, it only makes good sense to change the oil filter at every oil change.

Myth #8
  Heavier is better.
Thicker is better.
You can tell the viscosity of oil by feel (between your thumb and fore finger).
"I've used straight 30 weight for years."
Motor oil viscosity is not that big a deal.
Thicker motor oil is better for your engine and increases engine life.
One must use SAE 20W-50 motor oil if the vehicle has over 100,000 miles on it.
SAE 5W-20 is too thin to protect the engine.
Synthetic SAE 5W-30 is thinner than conventional SAE 5W-30 motor oil.
Straight weight oils (i.e., SAE 30) give better protection than multi-viscosity oils.

There are two main reasons why vehicle manufacturers recommend thinner or lighter viscosity grades of motor oil. First, a gain in fuel economy can be achieved with lower viscosity oil. At cold temperatures and at start up, lower viscosity oil will reduce internal engine friction. About 10% of the engine's horsepower is lost to internal engine friction, resulting in a drop in fuel economy. Additionally, vehicle manufacturers are struggling to meet Corporate Average Fuel Economy (CAFE) requirements set by the government and avoid paying associated fines. Any fuel mileage improvement associated with a lubricant use would be good for them, and lighter viscosity grade motor oil will make a difference.

Second, thinner motor oil is essential for easy starting, particularly in cold weather, and for proper lubrication once the engine starts. Today's smaller engines have smaller clearances and tighter tolerances between moving parts, and there have been some instances where camshaft damage has occurred because of inadequate lubrication with higher viscosity grades in colder weather. Thinner oils, such as SAE 5W-30, will flow faster than heavier motor oils during start-up and initial engine operation and will help protect the engine from excessive wear. Multigrade oil will also offer the same high temperature protection as single grade motor oil. Always check your vehicle owner's manual to select the proper viscosity grade based on the expected temperature range.

The viscosity grade(s) recommended by the vehicle manufacturer depend somewhat on engine design. Engine manufacturers have spent considerable time and expense experimenting with different viscosity grades and have indicated in the owner's manual the grades they feel will best protect the engine at specific temperatures. While one manufacturer's engine may require an SAE 10W-30, another manufacturer's engine may require an SAE 5W-20 viscosity grade. This is likely due to different tolerances within the engine or other engine design factors.

Myth #9
  All 2-cycle oils are the same.

Generally 2-cycle oils formulated specifically for air-cooled engines, such as chain saws, may contain additive chemistry not recommended for water-cooled engines, such as outboard motors. Ensure that the product you use meets the equipment manufacturer's requirements. Some oil marketers formulate products to meet both water- and air-cooled engine requirements.

Myth #10
  You can't use motor oil in a manual transmission.

Fluids recommended for manual transmissions/transaxles vary from manufacturer to manufacturer and are dependent upon application. The type of fluid recommended for a given unit will depend on a number of variables which include the low temperature fluidity required, the amount of gear wear protection needed, the effects of the fluid on synchronizers and the transmission/transaxle. Some transmission manufacturers may require motor oil to be used in the manual transmission. Other fluids used may be ATF, gear oil or a special manual transmission fluid, depending on variables previously mentioned. Always check the owner's manual to ensure the fluid being used has the proper performance requirements.

Myth #11
  Oil is oil ATF is ATF.
All oils are the same.

Motor oils and Automatic Transmission Fluids (ATF) are formulated differently. Motor oil is formulated to withstand the harsh combustion environment of an engine, while ATF is formulated to provide specific properties for a transmission.

Myth #12
  Adding a quart of ATF the day before an oil change will clean your engine. ATF added to the motor oil will clean the engine due to the high levels of detergent in ATF.

ATF does not contain detergent chemistry. ATF does contain dispersants, which have properties similar to detergents. But ATF is not formulated to withstand the combustion environment inside the engine. We recommends that you keep the fluids where they belong: motor oil in the crankcase, and automatic transmission fluid in the transmission.

Myth #13
  My owner's manual states my car requires API SF quality oil. I can't use API SL quality.

Using motor oil that meets all automobile manufacturers' warranty requirements is a key factor in developing repeat customers and safeguarding against unhappy customers with damaged engines. With all the changes in engine designs and oil formulations, determining which engine warranty requirements a given oil meets can be a frustrating experience.

To help simplify the process, the American Petroleum Institute (API), the Society of Automotive Engineers (SAE), and the American Society for Testing and Materials (ASTM) cooperate to determine engine oil performance needs, test requirements, and how to put this information into a consumer-friendly format. This format is called the API Engine Service Classification System and Guide to Crankcase Oil Selection. This guide establishes common designations used by automobile manufacturers in their owner's manuals and by oil marketers on their containers and in their literature.By comparing the API classification of the oil recommended in an owner's manual to the API classifications of various oils, you can quickly and easily determine which oils meet your vehicle's minimum requirements.

The API engine oil classification system is divided into two major categories. The "S" category designates oils for gasoline passenger car engines, and the "C" category designates oils for diesel-powered commercial truck engines. The "S" series is composed of SA, SB, SC, SD, SE, SF, SG, SH, SJ and SL. SL oils provide higher levels of performance than all the other "S" oils. API Categories SA through SH are obsolete, and oils labeled SL can be used in their place.

For modern vehicles, the ILSAC Certification Mark, known as the "Starburst," was introduced. ILSA- certified motor oils must meet the latest engine protection requirements of API, and must also pass certain fuel saving requirements. The starburst was defined by an organization of American and Japanese automakers - the International Lubricants Standardization and Approval Committee (ILSAC). The look of the Starburst was jointly developed by the motor oil and automobile industries in an effort to make it easier for the consumer to identify motor oils that meet the minimum performance requirements deemed necessary the automakers.

Due to the fact that the ILSAC requirements include a fuel economy requirement, the ILSAC Starburst symbol will typically be found only on lighter viscosity grades of motor oil such as SAE 5W-20, SAE 5W-30 or SAE 10W-30. These viscosity grades are generally preferred for use in cars made by General Motors, Chrysler, and Ford. These grades are also favored by the Japanese automakers.

Myth #14
  I don't drive under severe conditions.

Even with the best oil, after a while the additives are depleted and the oil becomes too dirty to function effectively. Although improvements in engines and oils and the use of unleaded gasoline have extended "normal-service" oil-change intervals to as long as 10,000 miles for some vehicles, the recommended interval for "severe-service" conditions is three months or 3,000 miles, whichever comes first. Because most drivers operate under severe-service conditions, We recommends a three-month/3,000 mile oil change interval. The time limit may come before the mileage limit. Your vehicle owner's manual specifies the correct oil-change intervals for the car-under both normal and severe-service conditions.

The automobile manufacturers set their oil drain intervals based on laboratory engine test results, fleet test results, and used oil analysis results. They also base intervals on the assumption that the consumer will follow recommended preventative maintenance practices, and maintain proper oil levels. Engines that operate with oil levels lower than the full level by as little as one quart, dramatically increase the severity of the conditions on the oil remaining in the sump. Even though some manufacturers recommend oil changes at more than 5,000 miles for normal service, We recommends oil and filter changes at 3,000 miles or three months, whichever comes first, unless the vehicle manufacturer recommends a more frequent change interval.

Myth #15
  Bulk oil is a different (lower) quality than bottled oil.

Consumers may believe that bulk oil is a lower quality because the price is generally less expensive than packaged product. With some oil marketers, this may be true; however, with our motor oil, our bulk oil quality is the same high quality as the packaged product. The price difference is generally the result of lower packaging costs.

Myth #16
  Adding oil additives means you can extend drain intervals.
Adding oil additives means I can get longer engine life.

Engine oil technology has rapidly advanced in the past decade, making today's high quality engine oils second to none. Now, vehicle owners have a choice between conventional, synthetic blends, and full synthetic engine oils positioned to provide the best protection for their application and driving needs. However, there are consumers who want to provide value-added protection to their engines through the use of engine treatments. Although there are several engine oil supplements on the market today, consumers must remember that the Original Equipment Manufacturers (OEMs) have stated in the vehicle owner's manuals (i.e. 1999 Silverado page 6-15), "Don't add anything to your oil. Your dealer is ready to advise if you think something should be added."

Myth #17
  The brand of oil used can cause the oil dipstick to rust.

Not true. Generally, rusting of engine parts indicates neglected maintenance or a severe service environment that requires more frequent oil change intervals. All high quality motor oils are formulated to help protect against rust and corrosion. However, to maintain that protection, the oil and filter must be changed according to the recommended maintenance intervals.

Myth #18
  A coolant leak is present only if the fluid separates into two parts.

When coolant contaminates engine oil, high fluid temperature will cause the water portion of the coolant to evaporate, leaving the ethylene glycol portion of the coolant behind. This results in a loss of lubricity of the engine oil product and sludge to form within the engine. Severe cases of coolant contamination or a neglected internal engine coolant leak could lead to complete engine failure.


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