Oils and Additives
Three ways you can improve your car's mileage and insure that it delivers good economy for a longer time are:
1. Understand the functions of oil in your engine.
2. Choose the proper oil for various operating conditions.
3. Change the oil and filter changed at the recommended intervals.
The functions of engine oil
What does oil do in your car's engine? If you answered "lubricate", you're only partially right. While oil is primarily a lubricant, it also performs a number of other functions that are vital to the life and performance of your engine.
In addition to being a lubricant, oil also dissipates heat and makes parts run cooler; it helps reduce engine noise; it combats rust and corrosion of metal surfaces; it acts as a seal for pistons, rings, and cylinder walls; it combines with the oil filter to remove foreign substances from the engine.
When combustion occurs, temperatures can reach 2000-3000°F. (1093-1648°C), while pistons can easily reach a temperature of 1000°F (537°C). The high heat load travels down the connecting rods to the bearings. Both tin and lead are commonly used in bearings and become very soft around 350°F (177°C).
Oil in the crankcase can reach 250°F (121°C) after warm-up and is supplied to the bearings at these temperatures.
As the oil circulates, it picks up heat, and may be 50°F (10°C) hotter than the crankcase oil. Flow and circulation of the oil keeps the bearings at a safe heat level and is essential to limiting bearing temperatures. A continuous circulation of large quantities of oil is essential to long engine life.
Types of engine oil
Engine oil service classifications have been provided by the American Petroleum Institute and include "S" (normal gasoline engine use) and "C" (commercial and fleet) applications. The following chart compares the latest API oil classifications with those previously used.
The American Petroleum Institute (API) SH quality level is a performance upgrade for gasoline engine oils from the API SG category. The American Society for Testing and Materials (ASTM) establishes engine tests for motor oils. Passing limits for these tests are the same for API SH oils as they were for API SG lubricants. However, the Chemical Manufacturers Association (CMA) has applied a Multiple Test Acceptance Criteria (MTAC), which is a statistically based methodology, to ASTM engine tests used to evaluate candidate oil.
The MTAC is:
• For oil run once, test data for each parameter must be a pass.
• For oil run twice, the average value of each parameter must be a pass.
• For oil run three or more times, one test may be discarded, and the average value of retained test data for each parameter must be a pass.
Previously for API SG and earlier categories, a pass in each engine test was sufficient regardless of the number of failures on the candidate oil before a test pass was obtained. Therefore, oils could be approved by failing a number of tests and bouncing one through for a pass.
In order to be certain that API SH oils can pass the ASTM engine tests to which MTAC have been applied, higher additive levels and a balancing of the chemical additive formula are required. More highly refined base oils are also helpful in meeting API SH specifications. The MTAC applied to ASTM engine tests results in performance improvements outlined below.
Test criteria (how oils are rated)
• Engine Rust
• High Temperature Oil Oxidation (oil deterioration)
• Piston Varnish
• Engine Varnish
• Engine Sludge
• Cam & Lifter Wear
• Bearing Wear
• Fuel Economy Improvement
Performance Improvement Over API SG
• Less rust
• Improved oxidation protection
• Less varnish
• Less sludge
• Less wear
• Better, fuel economy
Passing the ASTM Sequence tests with performance improvements over API SG allows oil to be labeled API SH and display the API donut symbol.
Thus far, we've discussed API SH. Now we'll talk about the tie-in with ILSAC. The American Automobile Manufacturers Association (AAMA) and the Japanese Automobile Manufacturers Association (JAMA), through an organization called the International Lubricant Standardization and Approval Committee (ILSAC), jointly developed and approved a specification for gasoline-fueled passenger car engine oils identified as GF-1. API and ILSAC have agreed on a single set of specifications that meet both API SH and ILSAC GF-1 with the exception of fuel economy and SAE grades approved. That is, in order to meet GF-1 an oil must meet API SH and the Energy Conserving II (EC-II) requirements. EC-II oil provides a 2.7% fuel economy improvement over reference oil in an ASTM fuel economy test that uses a laboratory engine. API SH has no energy conserving requirements. ILSAC GF-1 specifications apply to OW-X, 5W-X and 1OW-X oils where X can be 20, 30, 40 or 50. In contrast, API SH applies to all viscosity grades (multigrades and monogrades).
The API Donut Symbol can be displayed anywhere on the container for oils meeting the API SH chemical, physical and performance requirements. All viscosity grades are included and the oil does not have to be EC-II approved.
API designation SH and ILSAC designation GF-1 were introduced by the petroleum industry on August 1, 1993.
The API designation SJ has been adopted to engine oils available after 1996 and has replaced the former SH designation at the time of publication. The API SH designation may still be used in conjunction with an API C-service category.
Previously there were two energy conserving oil categories:
ENERGY CONSERVING AND ENERGY CONSERVING II: These may appear on the label as: EC or EC II. Effective as of October 1996 there is only one EC designation that is EC. The EC and EC II that were used in conjunction with API Service Category SH became obsolete after August 1997.
EC used in conjunction with API SH: These oils have produced a fuel economy improvement of 1.5 percent or greater over a standard reference oil in an ASTM test procedure. Oils meeting this requirement display the ENERGY CONSERVING will have a label in the lower portion of the donut shaped API Service Symbol.
EC II used in conjunction with API SH: These oils have produced a fuel economy improvement of 2.7 percent or greater over a standard reference oil in an ASTM test procedure. Oils meeting this requirement display the ENERGY CONSERVING II will have a label in the lower portion of the donut shaped API Service Symbol.
EC used in conjunction with API SJ: These oils have produced a fuel economy improvement of 1.4 percent or more (0W-20 and 5W-20 viscosity grades), 1.1 percent or more (other 0W-and 5W-multiviscosity grades), or 0.5 percent or more (low-multi viscosity grades and all other viscosity grades). Oils that meet this requirement and are properly licensed may display "Energy Conserving" in the lower portion of the API Service Symbol in conjunction with API Service Category SJ in the upper portion.
Oil viscosity
In addition to meeting the SH or SJ classification of the American Petroleum Institute, your oil should be of a viscosity suitable for the outside temperature in which you'll be driving.
Oil must be thin enough to get between the close tolerances of the moving parts it must lubricate. Once there, it must be thick enough to separate them with a slippery oil film. If the oil is too thin it won't separate the parts, if it's too thick it can't squeeze between them in the first place either way, excess friction and wear takes place. To complicate matters, cold-morning starts require thin oil to reduce engine resistance, while high-speed driving requires thick oil, which can lubricate vital engine parts at temperatures up to 250°F (121°C).
According to the Society of Automotive Engineers' viscosity classification system, an oil with a high viscosity number (e.g., 40) will be thicker than one with a lower number (e.g., l0W). The "W" in l0W indicates that the oil is desirable for use in winter driving. Using special additives, multiple-viscosity oils are available to combine easy starting at cold temperatures with engine protection at turnpike speeds. For example, 10W-40 oil will have the viscosity of l0W oil when the engine is cold and that of 40 oil when the engine is warm. The use of such oil will decrease engine resistance and improve your gas mileage during short trips in which the oil doesn't have a chance to warm up.
Some of the more popular multiple-viscosity oils are 5W-30, 10W-30, 10W-40, 15W-40, 20W-40, 20W-50, and 5W-50.
Consult your owner's manual or a reputable oil dealer for the recommended viscosity range for your car and the outside temperature in which it operates.
Additives
High-quality engine oil will include a number of chemical compounds known as additives. These are blended in at the refinery and fall into the following categories.
Pour point depressants help cold starting by making the oil flow more easily at low temperatures. Otherwise, the oil would tend to be a waxy substance just when you need it the most.
Oxidation and bearing corrosion inhibitors help to prevent the formation of gummy deposits which can take place when engine oil oxidizes under high temperatures. In addition, these inhibitors place a protective coating on sensitive bearing metals, which would otherwise be attacked by the chemicals, formed by oil oxidation.
Rust and corrosion inhibitors protect against water and acids formed by the combustion process. Water is physically separated from the metal parts vulnerable to rust, and corrosive acids are neutralized by alkaline chemicals. The neutralization of combustion acids is an important key to long engine life.
Detergents and dispersants use teamwork. Detergents clean up the products of normal combustion and oxidation while dispersants keep them suspended until they can be removed by means of the filter or an oil change. Foam inhibitors prevent the tiny air bubbles that can be caused by fast moving engine parts whipping air into the oil. Foam can also occur when the oil level falls too low and the oil pump begins sucking up air instead of oil (like when the kids finish a milkshake). Without foam inhibitors, these tiny air bubbles would cause hydraulic valve lifters to collapse and reduce engine performance and economy significantly.
Viscosity index improvers reduce the rate at which an oil thins out when the temperature climbs. These additives are what make multiple-viscosity oils possible. Without them, single-weight oil, which permitted easy starting on a cold morning, might thin out and cause you to lose your engine on a hot afternoon. If you use multiple-viscosity oil, it's this additive that helps your gas mileage during those short trips in cold weather.
Friction modifiers and extreme pressure additives are valuable in so-called boundary lubrication, where there is metal-to-metal contact due to the absence or breaking down of the oil film between moving parts. Friction modifiers, or anti-wear agents, deposit protective surface films that reduce the friction and heat of metal-to-metal contact. Extreme pressure additives work by reacting chemically with metal surfaces involved in high-pressure contact.
Synthetic oils
There are excellent synthetics and fuel-efficient oils available that, under the right circumstances, can help provide better fuel mileage and better engine protection. However, these advantages come at a price, which can be significantly more expensive than the cost per quart of conventional motor oils.
Before pouring any synthetic oils into your car's engine, you should consider the condition of the engine and the type of driving you do. Also, check the manufacturer's warranty conditions regarding the use of synthetics.
Generally, it is best to avoid the use of synthetic oil in both brand new and older, high mileage engines. New engines require a proper break-in, and the synthetics are so slippery that they can prevent this. Most manufacturers recommend that you wait at least 5000 miles (8000 km) before switching to a synthetic oil. Conversely, older engines are looser and tend to loose more oil. Synthetics will slip past worn parts more readily than regular oil. If your car already leaks oil (due to bad seals or gaskets), it will probably leak more with a slippery synthetic inside.
Consider your type of driving. If most of your accumulated mileage is on the highway at higher, steadier speeds, a synthetic oil will reduce friction and probably help deliver fuel mileage. Under such ideal highway conditions, the oil change interval can be extended, as long as the oil filter will operate effectively for the extended life of the oil. If the filter can't do its job for this extended period, dirt and sludge will build up in your engine's crankcase, sump, oil pump and lines, no matter what type of oil is used. If using synthetic oil in this manner, you should continue to change the oil filter at the recommended intervals.
Cars used under harder, stop-and-go, short hop circumstances should always be serviced more frequently, and for these vehicles, synthetic oil may not be a wise investment. Because of the necessary shorter change interval needed for this type of driving, you cannot take advantage of the long recommended change interval of most synthetic oils.
Most synthetic oils have been tested under the types of extreme conditions that you hope you will never duplicate within your engine. Under conditions of extreme heat, these oils can offer an additional level of protection which you cannot find in most conventional oils. Because of this, synthetic oils are popular for applications such as towing, racing or desert operation. They are also popular with those who are looking for that extra level of protection against engine wear or damage. Consider all of these factors if you are thinking about using synthetic oils.
Handling Used Motor Oil
It has been demonstrated that continuous contact with used motor oil can cause skin cancer in laboratory animals. It has also been documented that some substances found to cause cancer in laboratory animals can also cause cancer in humans. Therefore, it is important and prudent to minimize skin contact with used motor oil.
Skin contact with used motor oil can be minimized by following these safety precautions:
• DO follow work practices that minimize the amount of skin exposed and the length of time used oil stays on the skin.
• DO thoroughly wash off used oil as soon as possible with soap and water.
• DO wear long - sleeved shirts and use gloves made of material that oil cannot penetrate.
• DO remove and launder oil soaked clothing promptly. Discard oil soaked shoes.
• DON'T use kerosene, gasoline or other thinners to wash oil off the skin. They remove the skin's natural oils and can cause dryness or have serious toxic effects.
• DON'T over-use waterless hand cleaners. They also remove the skin's protective barriers.
• DON'T put oil rags in your pocket. This can cause prolonged skin contact.
Environmental Issues
Used motor oil is a valuable resource, but it can be a pollution problem if not disposed of properly. The following guidelines should be used when disposing of used motor oil:
• DO put used motor oil in a clean plastic container with a tight lid.
• DO take used motor oil to a collection point or put out for curbside recycling, as available.
• DON'T dump used motor oil in the trash, on roads, down drains or sewers, or on the ground.
• DON'T mix used motor oil with anything else (paint, gasoline, solvent, antifreeze, etc.).
Fluids and Greases
Types of grease
National Lubricating Grease Institute Certification Mark
It has long been recognized that the diversity of specifications for Automotive Greases, established by the Original Equipment Manufacturer (OEM), have made it difficult, if not impossible, for the marketer of lubricating greases to make available all the many specified products. With the issuance of specification ASTM D 4950 Standard Classification and Specification for Automotive Service Grease, it has become possible to offer the products needed to provide proper service of automotive equipment. This ASTM specification includes two Performance Groups:chassis lubricants (letter designation L) and wheel bearing lubricants (letter designation G). Performance categories within these Groups result in two letter designations for chassis greases (LA and LB), and three for wheel bearing greases (GA, GB, and GC). The automotive industry is in general agreement that the highest performance category in each group (LB and GC) is suitable for service lubrication.
The NLGI has developed an identifying symbol, i.e., the NLGI Certification Mark. The OEM's Owner's Manuals, which illustrate this Mark, advise users to use only those greases that incorporate the Mark into their product label.
Since only the highest performance categories are acceptable to OEM, only categories LB and GC will be authorized for use with the Mark. The three versions of the Mark are shown in the illustration.
Chassis greases
Most late-model cars no longer require chassis lubrication, but for those that do, the correct grease is generally an EP (extreme pressure) chassis lube. There's not really much problem, since it's about the only thing you can get in a cartridge refill that will fit in your hand-operated grease gun, if you lube your own car. Also, check for the new NLGI performance ratting mentioned.
Wheel bearing lubricant
There are two types of wheel bearing lubricant, low temperature and high temperature. The high temperature wheel bearing lubricant is the only one suitable for modern cars. Also, check for the new NLGI performance ratting mentioned earlier.
Master cylinder fluid
Always check your car's owners manual (if available) or even the cap on the master cylinder reservoir before adding brake fluid. DOT 3 and 4 are very similar fluids, though one may be specifically recommended by your particular manufacturer. DOT 5 (silicone fluid) is rarely used, but it is not compatible with systems designed for DOT 3 or 4 and, if used in the wrong system, would cause damage to the seals and other rubber components.
Brake fluid is used for both the brake master cylinder and the clutch master cylinder (if your car is equipped with a hydraulic clutch). Use only brake fluid rated DOT 3 or 4 or conforming to SAE Standard J1709. The rating can be found on the container. Brake fluid is typically hydroscopic, meaning it tends to absorb water from the atmosphere, both in the car and on the shelf. This is a good reason to change fluid at recommended intervals, and always use fresh brake fluid. Don't buy more than you are going to use, and purchase small containers rather than large so that you can keep them sealed for future use.
Brake fluid makes a wonderful paint remover. Be careful not to spill any on painted surfaces.
Automatic transmission fluid
Automatic transmission fluids can be broken down into two types, Dexron® III and Ford type F. These fluids are specific to the transmission using them. Don't assume that all Ford cars use type F, they don't!
• Dexron® III, sometime referred to as multi-purpose ATF. This replaces the old Type A, Suffix A, was recommended by GM, Chrysler and AMC between 1956-1967. It also supercedes Dexron® and Dexron ® II fluids. Ford cars 1977 and later with the C6 transmission or the Jatco transmission in the Granada and Monarch also use this fluid. Ford refers to this fluid as Mercon®, or transmissions where type H or CJ where recommended.
• Type F fluid is recommended by Ford Motor Co. for most late model Fords and certain imports, and contains certain frictional compounds required for proper operation in these transmissions.
There is not much of a problem here, since the bottles are clearly marked to indicate the type of fluid. If you are in doubt, check your owner's manual.
Gear lubricants
The American Petroleum Institute has developed specific lubricant service designations for automotive manual transmissions and axles, each designation referring to the performance required from a gear lubricant for a specific type of automotive service. These designations also recognize the possibility that lubricants may be developed for more than one service classification and consequently may be so designated. The system of designations replaces all previous API gear lubricant designations.
API GL - 1 - Designates the type of service characteristics of automotive spiral-bevel and worm gear axles as well as some manually operated transmissions operating under such mild conditions of low unit pressures and sliding velocities that straight mineral oil can be used satisfactorily. Oxidation and rust inhibitors, defoamers and pour depressants may be utilized to improve the characteristics of lubricants for this service. Frictional modifiers and extreme pressure agents shall not be utilized.
API GL - 2 - Designates the type of service characteristics of automotive type worm gear axles operating under such conditions of load, temperature and sliding velocities that lubricants satisfactory for API GL-1 service will not suffice. (obsolete)
API GL - 3 - Designates the type of service characteristics of manual transmissions and spiral-bevel axles operating under moderately severe conditions of speed and load. These service conditions require a lubricant having load carrying capacities greater than those which will satisfy API GL-1 service, but below the requirements of lubricants satisfying API GL-4 service. (obsolete)
API GL - 4 - Designates the type of service characteristics of gears, particularly hypoid in passenger cars and other automotive equipment operated under high-speed: shock-load, low-torque, and low-speed: high-torque conditions.
API GL - 5 - Designates the type of service characteristics of gears, particularly hypoid in passenger cars and other automotive equipment operated under high-speed: shock-load, low-torque, and low-speed: high-torque conditions.
Manual transmission lubricant
Many manual transmissions use gear oil viscosity of about SAE 80W or 90 grade. This is a gear oil viscosity and has nothing to do with motor oil viscosity. For instance, SAE 80W gear oil can have the same viscosity characteristics as SAE 40 or 50 motor oil.
However, not all-manual transmissions use gear oil. For years, Chrysler Corporation specified the use of automatic transmission fluid in their manual transmission cars. Some transaxles, both foreign and domestic, use either ATF or engine oil to lubricate the transmission. For this reason, it is always best to consult your owner's manual or your dealer if you are unsure about what sort of lubricant to use in your manual transmission.
Drive axle lubricants
Most conventional drive axles use gear oil viscosity of about 80W or 90 grade. Consult your owner's manual for more detail. Limited-slip or Positraction® rear axles usually require a special lubricant or in some cases, it is available as an additive, which is available from the dealer or parts store. If you do have a limited-slip differential, make sure you use only the correct lubricant, as the use of the incorrect lubricant can destroy the differential.
Power steering fluid
Power steering pumps are ordinarily lubricated with power steering fluid. Use the correct type for the car. Check the owner's manual if you are unsure.
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