Do you remember Castrol’s advertising tagline ‘Liquid Engineering’? I think those words are a good start towards understanding the importance of the oil which you choose. You really should know how to pick the right motor oil for your car.
The word ‘engineering’ usually makes me think about how things are held together. However, with oil it is more a case of holding things apart. When you fire the engine into action the cold-metal pistons and crankcase need to be kept from grinding away at each other. That’s the job of the oil.
The secret to automobile longevity is to know your oil!
Maybe you are already getting the idea that I think oil is very important. It helps the engine to start smoothly, it helps the engine to keep running, and it very much affects the longevity of the engine too. I don’t know about you, but it sounds important to me!
From the wide choice of car oil brands and types, the first response to ‘what kind of oil should my car use?’ must be to check with the manufacturer and check the owner’s manual. You might keep in mind that there may be some commercial tie-in influencing the manufacturer’s recommendation.
Let me see if I can help and explain the various car oil brands and engine oil types. Look at that oil container on the store shelf. Just exactly how many stamps and abbreviations can there be on one piece of packaging? Let me try and make it a little simpler for you. Seems to me there is one place to start, one word which is always present, but probably little understood.
That is what those numbers, 15/25 and 10/40, and their like, are talking about. I thought the chart from Elf was pretty and helpful. It is like Goldilocks’ porridge. Rather than “just right” in terms of temperature, you do not want your oil too thick, or too thin.
However, temperature does come into consideration too. If you have ever left a jar of honey in the refrigerator for very long, you will know that it soon becomes very thick, and will not pour easily. Its viscosity has become very low. Leave honey in the sun, it soon becomes almost watery, such a high viscosity is not good.
It is the same with oil. Cold and thick is not good for your engine, nor is hot and thin. Again, you want it just right. The numbers 10-30 represent the viscosity, resistance to flow, tested at 0 and 212 degrees Fahrenheit. With its higher numbers, an oil measured as 20-50 would have better viscosity when cold and when hot.
In respect of oil, it is the most important specification in the manufacturer’s manual, and you just know viscosity is a very technical and complicated topic when there is a whole website devoted to it.
There are broadly two types of oil. There is conventional oil from mineral hydrocarbons which have been drilled for and sucked out of the earth. Then there is synthetic oil which is totally manufactured in factories, by means of chemical processes.
The division is in the claimed quality, and is very noticeable in the price. A compromise is sometimes gained by blending the two types together. There is almost no doubt that engine oil is one of those times when you get what you pay for. Anything you see on the shelves of a U.S. store will do a job. But what you need to ask is will it do the right job in the best way.
Like the ‘NEW! Ingredient X’ which comes in your washing powder, there seem to be lots of things in your oil. Friction modifiers, viscosity-index modifiers, and anti-wear additives are helping the oil to be … well, more slippery and better oil!
Detergents though are about keeping the engine clean on the inside, preventing and removing sticky deposits. Continuing the cleanliness theme, if you think about having a bath in a tub with just bubbles, you might realize that foam inhibitors are a good thing
As you might have already realized, this is not a one-size-fits-all situation. I thought the most useful thing might be to give responses to an imaginary Frequently Asked Questions.
Five quarts can cost from just over $10 to more than $50. Sure, you can throw money at it, but usually that lower-mid-region of $20-30 will cover most people’s needs.
You must spend a lot of time sat on highways, probably at reasonable, steady speeds. Your car is under low-stress, the oil is under low-stress too. I have driven such cars which have done enough miles to get to the moon (a quarter of a million) and they still drive very well. Sorry, I don’t want to contradict, but a good branded, mid-priced, synthetic and traditional oil blend will probably be fine. Good news! You can probably save some money.
To keep it a little simpler, we’re looking at 4-stroke, petrol engines. If you’ve got a 2-stroke (as many chainsaws are), or you want to know the engine oil grades for a diesel engine, what can I say? For this article, I will just say ‘Use the correct oil!’ I might add ‘Sounds like another article’.
Yes! You might not love it, but buy the very best, probably the most expensive oil which meets the specification for your car. Almost by definition, low-mileage means short, infrequent journeys, with a relatively high frequency of colds starts which cause the maximum wear. Your engine actually needs all the help it can get! First thing in the morning, the oil has drained into the sump, and has to leap into action and get pumped. From being cold with low viscosity, to prevent metal against metal contact, a very good synthetic will help.
If you were to drive a car from 30 or 40 years ago, it would seem very noisy and crude. Modern cars are much more sophisticated and it makes sense that they often need the modern, more sophisticated, synthetic oils. With modern, high-performance engines it is often mandatory for you to use expensive, but high-performance synthetic oils.
Older cars can also do with a little help. I’ve no first hand experience yet, but a friend has had a good experience, and I intend to try Valvoline’s ‘Max Life’ when I can. I like the idea that it will help improve the condition some of the engine’s seals.
In short, almost certainly. Synthetic motor oil is chemically engineered, keeps it shape, is purer, performs better in extreme situations, it is better oil. But only buy it if you need it.
They are indicators that the oil has met certain standards. There is a massive amount of detail which I think would make a good article on its own. As a small example, with ‘SAE 5W-20’ oil, the initials mean it has been tested by the Society for Automotive Engineers, and “5” is the cold-temperature viscosity with the "W" meaning ‘winter’.
I think that any car which has done 50,000 or more miles, would probably benefit from being cleaned out with flushing oil. It is either a DIY or inexpensive garage job. I once solved a potentially very expensive, noisy hydraulic cam problem by flushing the engine out … twice!
If your car is not used in any extreme way, get the right weight, that is viscosity, and spend something around $25, and you won’t go wrong. I saw a Mobil, fully synthetic, at less than that at Walmart the other day.
Check your oil level regularly, probably once a week for an older car. Too little oil can bring metal on metal contact, and wreck an engine. BUT too much oil can cause pressure to build and blow gaskets.
I like people who are experts at what they do. They often achieve this status by concentrating on one thing. Rather than buy engine oil from one of the big oil companies, I like the companies devoted to producing a narrower range of products, with a known name. This is one time I tend to follow the sheep and join those making Penzoil the U.S.A.’s best-selling motor oil.
There are some more technical aspects which we could talk about, but I hope I’ve encouraged you in the right direction of thinking a little about the importance of the role which oil plays. For my part, I’ve always thought that good quality oil, changed regularly, is the best way I can look after my investment in motor vehicles.
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