Slippery Stuff

Engine lubricants are the blood of a vehicle’s engine. Every technician has heard or used that analogy, yet a large proportion of Canadian motorists pay less, and sometimes a lot less, than two dollars for a litre of this vital fluid. Does 88 cent oil in a 35,000 dollar car make sense? It does if the product is perceived as a commodity, and most consumers do see engine lubricants as essentially the same product. Changing that perception takes a little knowledge abut what engine lube does, and how it does it.

What it does

“Motor oil” isn’t a flattering or truly accurate term for the lubricants we use in modern engines. Modern products must lubricate, yes, but also cool, seal, counteract harmful chemical reactions within the engine, fight corrosion and trap dirt and other particulates. Tom Smith, technical director for Valvoline, describes the major area of consumer misunderstanding in engine lubricants: “People don’t have any understanding of the API (American Petroleum Institute) classification. They have some limited understanding of viscosity grades, but I think, in terms of the overall system of how we describe our oils to the consumer, the consumer doesn’t have a very good understanding. From a performance perspective, consumers don’t understand how severe stop and go type driving is, and how relatively speaking, going out on the highway and driving at 115 km/hr isn’t hard service on your vehicle.”

The notion of short distance, stop and go driving as severe service is easier for the consumer to grasp if the technician explains the consequences of repeated driving without operation at normal engine temperatures. Moisture and the formation of corrosive acids may be a definite problem, and in extreme cases, usually when combined with poor maintenance, sludge formation can occur.

Additives are important

While all the major players in the lubricant industry use good quality base stock, the additive packages are key to matching an oil product with a specific vehicle and driving style. Jim Arner, technical manager for Texaco Lubricants Company, describes some of the ways in which additives function: “The additive packages help improve performance by a couple of mechanisms. One mechanism is that the additive will bond to metal surfaces and provide a chemical layer on the metal surfaces. That protects against corrosion, water and any corrosive acids that may be formed in the engine. A lot of these aftermarket additives talk about bonding to surfaces. If you have a polar molecule, there will be bonding with anything that is polar or induced polar. So where they’re talking about how it preferentially bonds, that’s not saying anything new to an oil chemist, but to a layperson, that sounds interesting. You have a non-destructive chemical, where as long as this chemical film is there, there aren’t going to be any problems.”

Detergents are another component of engine oils and do dual duty in modern engines. One function is to encapsulate dirt and clean the engine internally. The other is a consequence of a natural property of detergents, whether in motor oil or the family washing machine: alkalinity. The alkalinity of detergents is a useful feature because it neutralizes the organic acids which are a natural by-product of the combustion process.

Another class of additives are oxidation inhibitors. Oxidation inhibitors are essential because engine operating temperatures are high enough to accelerate the reaction of the oil with oxygen. Oxidation can result in oil thickening as well as sludge and varnish formation. 210 degrees Fahrenheit is an ideal temperature for evaporating unwanted contaminants, but 250 degrees renders an oil prone to oxidation. At temperatures over 300 degrees, the process accelerates. One moral to the story is that even brief engine overheating incidents should prompt a preventative oil change. Oxidation inhibitors are also noteworthy because they are affected by a major change in engine oil formulation which is coming in the very near future: the reduction in phosphorus. Tom Smith explains: “Phosphorous is in the engine oil in the form of zinc dialkyl-dithiophosphate. This is the primary anti-wear and antioxidant in an engine oil. So down the road there will be an even greater risk that new oils won’t give the same wear protection that older oils did. Phosphorous levels have already been reduced in oils, but we don’t believe that it’s been reduced enough that it’s going to hurt anything. But it is certainly a potential that is coming down the road.”

With OEM requirements driving oil development, modern engine designs place decreased emphasis on wear control due to new bearing materials and tighter production tolerances. Existing engines, however, will need at least the current amount of protection, and maybe more, creating the possibility that the newest API rating may not be truly retroactive to earlier grades, as is generally the case now. It’s definitely premature to predict that some future API ‘SJ” or “SK” grade oil will provide inadequate anti-wear performance in older engines, but the mere possibility opens the door for specialty lubricants designed for older engine designs.

Which viscosity?

While the simplest and easiest way to deal with the viscosity question is to consult the vehicle manufacturer’s specifications, in many cases new additive formulations and the option of mineral or synthetic base stocks have allowed a range of viscosities which exceed the OEM’s requirements. Is 5W always preferable to 10W in multigrade oils? Vinzon Pingol, associate trade marketing manager for Castrol Canada declares: “The reason why a 5 is better is than a 10 weight is that in cold, extreme temperatures, the pour point and the flow of the oil is better. In the summertime, this is not a factor because thicker oil can thin out. So if you go to a thicker oil, it will thin out and give you better protection than a 5W-30. I can’t see a lot of people needing to use a 0W30, unless they’re in a place like Ottawa, Sudbury, North Bay when it gets brutally cold for long snaps. You may need that extra three, four degrees so the oil doesn’t seize up on you. But most of those places have block heaters anyway. Sometimes it’s just a market thing. OW30, I get better protection, especially in colder temperatures. Is it really necessary? Not really, because it’s not going to get to minus 40 for weeks on end, so the driving conditions aren’t so brutal.”

Honda is pioneering OE fill for 0 weight oil in the hybrid-power Insight. Very efficient vehicles like the Insight can benefit from the easy flowing 0 weight, but as of yet, OEM’s have not indicated a widespread switch to this viscosity. A grade which is catching on, however, is 5W-20, now the factory fill for several Ford and Honda models. Like the 0 weight products, the narrower 5W20 formulation is designed to take advantage of advanced engine designs and to reduce internal friction for slightly better fuel economy. The OE commitment to 5W20 is serious, with Honda currently advising its dealer network to install bulk capacity for the new grade, and to fill 10W30 requirements from bottled product. Castrol’s Pingol points out: “The tolerances of engines have been significantly reduced. One of the main reasons that manufacturers are recommending 5W30 and 5W50’s is because it’s a thinner oil and therefore the engine doesn’t have to work as hard to run. Just imagine molasses in your engine. Something that thick makes it harder for the engine to operate. The problem is, it is a trade-off. Does a thinner oil protect your engine as well as a thicker oil? If you’re using a 5W30 versus a 10W30, you’re probably looking at a savings in fuel efficiency of a tank or two per year. Not a huge savings, but it is certainly there, and the manufacturers can say to the government “we’re complying”, but it doesn’t necessarily mean that the engine is getting the best protection that your engine can afford. So when they recommend that you use a 5W30, you don’t necessarily have to use a 5-30, that recommendation is based upon fuel efficiency. You can use
10-30 and it will protect your engine as well and keep your warranty intact as long as you’re using an API-specified engine oil. The standard right now is SJ. And for any new car out there right now, they’re recommending API SJ.”

Do Aftermarket Additives Work?

Motor oil additives have been around almost as long as oil itself, and many have considerable brand equity with the motoring public. Do they work? Texaco’s Arner gives additives a qualified “yes”: “What you have is people who try to extend the life of their oils by putting in these additives. They, in turn, could upset the balance. And that’s why all the OEM’s are against them. And of course the oil compounders are against it because we say those additives are added in the first place. The biggest thing you have to remember, of course, is the additives that are in the oil are designed to take care of the dirt for a period of time; then you can drain it out. And it’s the dirt that builds up in the engine that you want to get out. And people want the quick band-aid so they’d rather spend 25 dollars on these additive packages to fortify it. In some cases these additives work well. If you’re going to be towing a trailer and you know your transmission is going to be running hot, there are some additives that are basically say, ‘put this in your transmission and you will improve the oxidation resistance by 15 percent according to these test methods’. They work at times. Now, for motor detergents, say you’ve got gunked up rings or your lifters are sticking. If you throw your “super motor detergent” in there, it’s got extra-high detergency, and maybe you’ve got some extra additive in there for anti-wear. It tells you to put it in for about 150, 200 kilometres and then you drain it out, because you want to get the dirt out of the engine. That’s the whole process with the combustion process, you want to get the dirt out. And that’s the most damaging stuff. If we lived in an ideal world, you could have a thin film of straight mineral oil and never have any worries. But it’s all the other things introduced that place severe loads on the engine oil and the engine.”

Arner’s point about dirt applies in a general sense to all engine oils: they’re used up like any consumable during normal engine operation. And abnormal conditions such as high-mileage, internal damage and severe service all use up an oil’s protective capabilities faster. As a result, there is simply no one universal drain interval. No one ever damaged an engine, however, by changing oil and filter too often. Five to six thousand kilometres is still a safe margin for most drivers.

While there is far more to engine lubricants than can be covered in any one article, the oil industry offers a wide range of support for interested technicians, ranging from Internet sites to 800 tech telephone lines. It’s easier for today’s technicians to get expert answers about engine oil products than ever before, and that’s fortunate because the range and amount of technology in today’s products is high and growing. Good advice from a good technician can go a long way toward saving the consumer from low-price, low performance motor oil. SSGM

MOTOR OIL: WHAT’S INSIDE

Engine Lubricants contain a surprising amount of chemistry for such a low-cost petrochemical product. A typical engine oil contains:

Detergents — Surrounds and disperses soot, sludge, and other solids and semi-solids. Detergents are consumed over time and are a major reason for the need for frequent oil changes in severe service conditions.

Oxidation Inhibitors — Prevent radical formation which causes oil thickening and the formation of sludges, varnish and organic acids.

Anti Wear Additives — Often sulphur, phosphorus or zinc-based, anti wear agents create a film on internal engine parts, bolstering the oil “wedge” protecting critical wear components such as bearings and cylinder walls.

Corrosion Inhibitors — Fights corrosion of internal engine parts caused by condensation and acid formation within the crankcase, both by neutralization of acids and with a protective film on metal surfaces.

Anti-Foam Additives — Reduce the excessive foaming of the oil caused by entrainment of air, especially at high RPM’s, over filled crankcases, or high-performance vehicles with no windage tray. Excessive foaming can cause oil pump cavitation and loss of oil pressure.

Friction Modifiers — Reduce internal engine friction for improved fuel efficiency and performance.

Pour-Point Depressants — Allow free-flow of the oil at temperatures typically encountered in Canadian winters. Without pour-point depressants, many oils would congeal at as little as minus five degrees Celsius

Viscosity index Additives — Allows relatively thin five or ten weight oils to protect as well as 30 to 50 weight grades at 100 Celsius.

MOTOR OIL FAST FACTS

“Normal” oil pressure is roughly 10 psi per 1000 engine RPM

Viscosity is the only property of motor oil which can alter engine oil pressure

It can take 20 to 25 minutes of highway driving to bring motor oil up to its normal operating temperature

A leak of one drop per minute from an engine will add up to 28 litres per year

A typical engine burning one drop of oil per firing stroke will use a litre of oil every three kilometres.

Source; Pennzoil Tech Bulletin G-01-B