Pennzoil

A lot of people wonder what modern motor oil is, how it works and what all those confusing grades and symbols mean. Well, keep reading. You’ve come to the right place.

 

WHAT IT IS

Engine oil’s primary functions

Engine oils are complex mixtures of base oils and additive components designed to perform a variety of tasks: separating and lubricating moving parts, reducing engine wear, helping prevent deposits from forming on internal engine components, removing and suspending dirt and contaminants in the oil until these contaminants can be removed at the next oil change, cooling engine parts, enhancing engine fuel economy, providing protection over a wide temperature range and even helping to protect the emissions system. In other words, they do a lot more than just lubricate.

 

Regarding emissions systems, catalytic converters, as you know, can deteriorate over time. A high-quality motor oil helps protect the emissions system by minimizing its own impact on these devices. To assure base quality, always look for the American Petroleum Institute (API) Starburst and Donut. We’ll discuss those in more detail further down.

 

Engine oil formulation

 Engine oil is comprised of two basic components — base oils and additives. The base oils constitute 75 to 85 percent of the total, while additives round out the remaining 15 to 25 percent.

 

These additives, known collectively as the Performance Additive Package, are comprised of dispersants, detergents, anti-wear additives, friction modifiers, antioxidants, anti-foam additives and corrosion inhibitors. In addition to the Performance Additive Package, motor oil additives also include a viscosity index improver and a pour-point depressant.

 

 

 

Dispersants

A dispersant helps keep sludge from forming on internal engine parts by suspending contaminants in the oil until they can be safely removed at the next oil change.

 

Detergents

Detergents operate on high-temperature surfaces, such as the piston-ring area and the piston under-crown, helping to prevent deposits. These detergents get consumed over the life of your oil change.

 

Anti-Wear Agents

Anti-Wear Agents form a protective coating on metal surfaces. They also provide an antioxidant boost. Anti-wear agents operate under high temperatures and high load conditions, particularly protecting cams, lifters, piston rings and cylinder walls. Anti-wear agents cloak these surfaces in a “sacrificial layer” or film, which is consumed in the protective process. Without this “sacrificial layer,” metal-to-metal contact would occur. Like detergents, anti-wear agents also get consumed over the life of your oil change. Another reason you should always change your oil at recommended intervals.

 

Friction Modifiers

These do what you think; they reduce friction under high loads and high temperatures, helping to maintain peak efficiency and fuel economy. The effectiveness of these additives diminishes over time as the oil ages.

 

Antioxidants

Oxidation results from exposure of the oil to oxygen at high temperatures. It’s not a good thing. The results of such exposure can accelerate the aging of the oil contributing to oil thickening, sludge and deposits. Antioxidants help slow oxidation in the oil to help keep engines running clean.

 

Anti-Foam Additives

Foam-causing air bubbles create a variety of problems in oil. They make oil harder to pump to vital engine parts, reduce the oil’s lubrication effectiveness and inhibit the oil’s ability to help keep the engine cool. A foamed-up oil can result in serious engine damage. An anti-foam additive helps prevent these problems.

 

Rust and Corrosion Inhibitors

It might sound strange, but internal engine parts can be subject to rust and corrosion. Rust and corrosion inhibitors coat metal surfaces, protecting against these hazards.

 

Viscosity Index Improvers

The Viscosity Index measures an oil’s ability to resist changes in viscosity as temperature changes. Viscosity Index Improvers utilize polymer additives to help maintain oil viscosity over a wide range of temperatures. The use of Viscosity Index Improvers allows the formulation of multi-grade engine oils, such as 10W-30 and SAE 10W-30.

 

Pour Point Depressants

These are used in multi-grade oils to provide good oil flow at low temperatures.

 

OIL GRADE DESIGNATIONS

Oils use a rating system developed by SAE, which is the Society of Automotive Engineers, to classify oil by viscosity. We’re all used to seeing designations like SAE 5W-30 or SAE 10W-30, so let’s talk about what they really mean.

 

For multi-grade viscosity oils, the cold-temperature viscosity is labeled with a “W,” which stands for “winter.” Thus, in an SAE 10W-30 oil, the “10” is the cold-temperature viscosity rating, the “30” the high-temperature viscosity rating. This combination provides an oil that flows well at low temperatures, but still protects the engine at high temperatures.

 

For comparison’s sake, SAE 5W-30 and SAE 0W-30 will flow better at even lower temperatures than 10W-30 while still providing protection at high temperatures. Just remember, the W stands for winter.

 

The API/ILSAC “Starburst”

You see this symbol on many quality oils. API is an acronym for the American Petroleum Institute. The institute’s Starburst stamp of approval — it reads “American Petroleum Institute Certified” — was created to help consumers identify engine oils that meet specific performance standards set by vehicle and engine manufacturers.

 

 

The Starburst identifies engine oils recommended for a certain application, such as “For Gasoline Engines.” To carry this symbol on the container, the oil must meet the most current requirements of ILSAC, which is the International Lubricant Standardization and Approval Committee, a joint effort of U.S. and Japanese automobile manufacturers.

 

The Starburst is typically found on the front label on SAE 0W-20, SAE 0W-30, SAE 5W-20, SAE 5W-30 and SAE 10W-30 motor oils.

 

 

 

 

The API “donut”

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Another identifier on motor oil containers is the API “donut” typically found on the back label. It’s divided into three parts. The top half of the circle (2) indicates the API service rating, also called the performance level. The center of the circle (3) notes the SAE viscosity, which we just discussed. The lower half of the circle (4) indicates whether the oil has demonstrated certain energy-conserving properties.

 

In the top part of the donut, the words “API Service XXXXX” (5) indicate the type of engine and performance the oil provides. "API Service SM": the "S" means the current rating for Service Station oil (for gasoline engines) and "M" means the current level of service. Or it will say “API Service CJ-4.” API service CJ-4 means “C” for commercial engines (diesel engines) and J-4 where "J" is the current performance level and "4" indicates a 4-stroke diesel (a 2 will be used for 2-stroke diesel engines).

 

Check your owner’s manual for the recommendation for your vehicle. Older vehicles can use the current designation. All designations are compatible with those that preceded them. Only the current API categories are indicated within the donut.

 

Myth: Once you switch to synthetic oil you can never switch back.

This is one of the most persistent myths about synthetic oil Ñ and completely untrue. You can switch back and forth at any time. It is advisable that you use the same oil for top-ups if needed, thereby giving you the best protection from the oil that you have chosen.

 

Myth: You shouldn’t use synthetic oil in an older vehicle.

The myth is rooted in the idea that synthetic oil is "slipperier," lower in viscosity, or not as compatible with seals and will therefore leak or leak more in places conventional oil might not. Synthetic oils will enhance the engine protection in older vehicles just as they do for new engines.

 

Myth: You should break in your engine with conventional oil before you start using synthetic.

Again, there’s no manufacturer we’re aware of that makes this recommendation. Mercedes, Porsche, Corvette, some Cadillac, Volkswagen, Hyundai and several other manufacturer’s cars come from the factory with synthetic oil.

 

Myths: Using a synthetic oil voids a car’s warranty.

The only engines that specifically exclude the use of a synthetic motor oil are some Mazda rotary engines.

 

Myths: Synthetics made from Group III base oils are not true synthetics and are not as good as PAO-based synthetics in Group IV.

Synthetics made from Group III oil can, in some cases, outperform those made in Group IV oils in some areas of performance.