Engine oil development generally starts out with “crude mineral oil”. It is a fossil fuel, made naturally from decaying plants and animals (hence the term, “mineral oil”). Crude oils vary in color, from clear to black, and in viscosity, from water-like consistency to a near solid depending on geography, region of the world, and other factors. Why does crude need to be refined and what happens in the process? Crude in itself cannot be used for any specific application requiring consistency Hydrocarbon molecules of various lengths get refined More stable and categorized molecular structures come from each refining process Impurities are removed, making the end product more effective and useful How is crude oil refined? There are several methods to stabilize and manage the complex mix of hydrocarbon molecules found in crude Separation (e.g.: Solvent extraction) • Removal of undesired molecules Conversion (e.g.: Hydrocracking) • Changing bad molecules into good molecules Synthesis • Breaking down all hydrocarbon molecules into smaller parts • Build up desired molecules from smaller ones. What products come out of the refined crude? Different hydrocarbon molecule chain lengths all have progressively higher boiling points in the refining process, so they can all be separated by fractional distillation. Here are some of the products derived from the refining process: Petroleum gas Motor fuel Kerosene Gas oil or Diesel distillate (used for diesel fuel and heating oil) Fuel oil Chemicals for plastics and other polymers Residuals (waxes, coke, tar & asphalt) Lubricating oil base stocks Once each product has been pulled out of the crude oil in the refining process, it is then purified and blended with other ingredients until completed.

The viscosities and characteristics of oil vary between brands and base stock origin. In the early 1900s, consumers needed some way of classifying what oil would work best for their engine. They needed some recognizable standard. To answer that need, the American Petroleum Institute (API) and the Society of Automotive Engineers (SAE) standardized were born. What do SAE numbers mean? SAE ratings measure the viscosity, or thickness, of oil at a constant temperature. Thin oil flows more easily (it can even be close to the consistency of water) and has a lower viscosity number, while thicker oils have a higher number and are more resistant to flow (such as molasses or honey at room temperature). Substance Viscosity @ Room Temp (mPa-s) Peanut butter 250,000 Ketchup 100,000 Chocolate syrup 25,000 Honey 10,000 Molasses 8,700 Maple syrup 3,200 SAE 40 motor oil 350 SAE 30 motor oil 200 Olive oil 80 Mercury 2 Water 1 Gasoline 0.5 This viscosity is then expressed in the amount of time taken for a standard quantity of oil to pass through a standard orifice at a given temperature (measured by a viscometer). The thicker (higher viscosity) of oil, the slower it will flow, commonly measured in kinematic and absolute (centistokes - cSt) values. Higher values mean more viscous fluids. What is “Multi-weight” oil? “Multi-weight” ratings indicate viscosity at both cold and hot operating temperatures. For example, SAE 10W-30 tells us both low temp and high temp viscosity. The “W” stands for “winter” (not weight), so receives a viscosity rating of ‘10’ at colder temperatures. It conversely receives a rating of ‘30’ (a thicker, more viscous consistency) at higher temps. The viscosity index improver (see “Oil Additives”) produces a thickening effect at high temps but is dormant at low temps, thereby producing “multi-grade” oil. Exposed to extreme conditions, these improvers can “shear” and lose their effectiveness. Most oils will meet the viscosity requirements of at least one of the “W” grades. With the right quality base oil and proper refining techniques, the finished product needs no additives to improve cold temperature performance. Nevertheless, some receive a “straight weight”, or single grade SAE classification, indicating that product has been formulated only for high temperatures. SAE 30 is one example of a single grade oil. What is an ‘API rating?’ As the oil industry began innovating new products and additives to enhance performance, the need increased to classify each oil accordingly. In 1924 the API answered the call by establishing a grading system for both gasoline and diesel engine oils. They did so to help end users know what to expect from their oil’s performance and quality. API’s classification does not point to oil viscosity (see the “SAE Viscosity Grades” section), but primarily to the automotive industry’s drive toward fuel efficiency and lower emissions standards. The automotive category of the API rating system shows the “S” service grade, while the “C” category meets requirements suited to diesel engines. Each progressive suffix indicates the latest API oil standard. Starting with “SA” (straight mineral oil) in the 1930s, API standards moved through the alphabet, skipping “SI” and “SK” from the sequence. As auto makers came under increased pressure to develop more fuel efficient vehicles, oil formulations were changed to accommodate. Today, the latest API rating is “SM”, with “SN” soon to follow. For engines designed for use in lawn mowers, the highest API rated oil may not always be best. The same additives which enhance fuel economy for your car may do nothing to protect from the severe abrasion and corrosion exposures inherent in the life of your lawn mower. See “Oil Additives” section for more guidance on the most common components used to get the best performance from your machine.

Modern chemistry has done wonders to enhance performance and adjust properties to suit the application and maximize the base oil’s performance potential. Most conventional oils contain about 93% oil and 7% additives, while synthetic oils contain up to 20% additives. Exmark does not recommend the use of aftermarket additives. Our oil has been carefully formulated for your engine and the type of service it will see. Further additives may change critical performance properties and damage your engine. Viscosity index improvers much like tiny ball bearings which expand at higher temperatures to produce a thickening effect; they help with cold temperature start-ups. They can also shear and lose their effectiveness in prolonged, harsh conditions. Anti-wear additives, usually a zinc-phosphorus compound to provide barrier lubricity on sliding metal contact points. Detergents and dispersants especially effective as a diesel additive to neutralize impurities and remove deposits to prevent sludge. Anti-foam agents to prevent loss of lubrication, pitting and cavitation. Pour Point Depressants which lower the oil’s freezing point (important when operating below 0 degrees F Seal swell agent to prevent oil leakage. Antioxidants to increase the oil’s stability. Corrosion and rust inhibitors to protect against the effects of condensation during prolonged storage periods.

Clear away residue from the manufacturing process The process of manufacturing a new engine inevitably leaves foreign material deposits and resins behind. Despite every effort to keep factory environments sterile, no engine manufacturer can avoid this challenge. Typically, those particulates need to “burn off” within the first few hours of operation, or get drained out at the first oil and filter change. Factory-installed oil is designed with this in mind. While most high quality oils enable proper piston ring seat from the very first engine start, break-in oil gives your engine its best opportunity to be cleared of manufacturing particulates no manufacturer can completely prevent. Piston ring seat In days gone by, engine components didn’t fit to the same exacting dimensional tolerances they do today. When that happens within an engine cylinder, and the piston doesn’t quickly and closely mate to the cylinder wall, “blow by” can occur. Combustion gases escape the combustion chamber past the piston rings into the crankcase section of the engine, causing damage and reducing power. New manufacturing technologies now have enabled even the smallest manufacturers to produce components with exceptional consistency and tight dimensions. As a result, engine parts mesh with very little operating time, and your engine manufacturer can publish lower break-in hour requirements.

Myth: “I broke in my engine on Brand X; I can’t switch brands.” Fact: While it does help your engine to use oil with the same additives and formulation, using oil consistent with your engine manufacturer’s SAE & API recommendation is the first priority. Myth: “Never mix brands of engine oil.” Fact: Different oils will have different additive combinations, so routinely mixing oils within the same SAE grade may not be a sound maintenance practice but on occasion will not harm your engine. Again, follow your engine manufacturer’s recommendation. If you introduce a different SAE viscosity grade, make sure you drain out the old oil first. Different SAE grades will not mix well in your engine. Myth: “Paraffinic base stock oils can cause wax build up or sludge.” Fact: False. Even high quality oils come from paraffinic base stocks. Contrary to popular myth, “paraffin” does not mean your oil contains candle wax. Paraffin molecules in fact enhance base stock stability, thus helping to prevent sludge. Myth: “The ‘normal’ oil change interval recommended by my engine manufacturer can be extended with use of higher quality oil.” Fact: Using higher quality oil in your engine will in fact help enhance the life of your engine, but no oil on the market will enable you to extend change intervals. Today’s recommended oil change intervals are not conservative and do not allow for any warranty consideration if they are exceeded. Myth: “Poor quality motor oils can cause sludge.” Fact: While poor quality oil doesn’t help avoid sludge, it doesn’t often cause sludge. Dirt, soot, moisture, bad fuel, oxidized oil and other elements do more to create sludge in your engine than anything. The best prevention starts with high quality oil, and continues with regular oil and filter changes.

Our engineers considered several key risk factors when it comes to protecting your engine. All of these elements require at least one of the following: detergency, dispercancy and anti-wear additives. Without them, here’s what can happen: Excessive wear The build up of deposits behind the rings forces them against the cylinder Deposit build up Preventing ring movement, effective sealing and leading to ring sticking Lacquer Film of unstable oil/fuel residue on piston skirt Ring sticking Leading to loss of power, high oil consumption and increase of blow-by gases Bore polish Piston rings and deposits polish honing marks in cylinder walls, leading to poor oil retention, wear and oil consumption Blow-by gases Containing unburned fuel and water, pass into the sump and attack the oil