Today, I shall open up a new chapter on preventive maintenance as I've just realise that I have not wrote about anything on maintaining an engine. This, and the next few subsequent posts we will focus on the engine area in terms of performance, longevity and driveability.
Engine Oil
You may think that every 5000km an oil change is sufficient. But please ask yourself the below questions :
- Do you know what oil are you using? I tend to ask my customers that and some aren't able to give me a direct answer. "I don't know laaaa, foreman put in for me one". You have to be aware of what's being poured into your engine in terms of oil brand and viscosity. Oil viscosity is pretty important in the long run and also in terms of fuel consumption and performance. They affect each other.
The common grades being used are 5w-30, 10w-30, 5w-40, 10w-40, 15w-40, 20w-50. There are also less common grades such as 0w-30, 0w-40, 0w-50 and so on. In a general automotive term, 5w-30, 5w-40 and 5w-50 are usually fully synthetic oils whereas the 10w30 and 10w40 are usually semi synthetics. There are cases of 10w30 minerals as well. 15w-40 and 20w-50 are usually minerals. Old school mechanics will swear by their 20w-50 for long term protection. However, most people dont know that a Supra uses 5w-30 or 10w-30.
Back to the question, you need to know what oil are you using. From there and then I can advise you on what's to be used. Okay, smaller cars such as Kancil, Kelisa, 1000cc or below generally run on 30grade, regardless of 5w or 10w. These engines are tiny and have tight clearances. Using a heavy oil has no benefit to the driver.
I usually recommend 40grade to customers driving cars that are above 1000cc such as Myvi, Swift, Wira, or any other car for that matter. Yes I understand that some of your owner's manual do state that 30grade is to be used. However, keep in mind that engines wear and tear over time and clearences between the bearings get wider over time. Just a note, campro engines run generally rough and noisy and it says 30grade on the manual, you guys may want to try 40grade.
Also, too low of a viscosity and the oil may or may nor shear and will lose film strength at high temperatures. IF it is too thick, it will also not circulate at low temperatures.
Usually, I do not refer to the 5w or 10w figures as there is no winter in Malaysia. However, on some special cases I'd recommend 10w to older cars and not 5w. Mind you, take a bottle of 5w-30 and 10w-30 and shake them and compare. You will notice that the oil in the 5w feels a tad thinner. I cannot find time to find the explanation on why is this so but all I know that (referring to the "special case"), the 5w-40 oils tend to burn and consume faster than a 10w-40 oil in engines that have compression loss aka older engines. I assume that the 5w oils have more polymers in them making them a little bit thinner by feel. Polymers are blended into the engine oil so allow them to change viscosity over temperature. Monogrades are also available which I personally think will be better. . I personally do not think that multigrades are needed here in our country, Malaysia.
This is taken from micapeak.com and realclassic.co.uk :
"Multi viscosity oils work like this: Polymers are added to a light base(5W, 10W, 20W), which prevent the oil from thinning as much as it warms up. At cold temperatures the polymers are coiled up and allow the oil to flow as their low numbers indicate. As the oil warms up the polymers begin to unwind into long chains that prevent the oil from thinning as much as it normally would. The result is that at 100 degrees C the oil has thinned only as much as the higher viscosity number indicates. Another way of looking at multi-vis oils is to think of a 20W-50 as a 20 weight oil that will not thin more than a 50 weight would when hot.
Multi viscosity oils are one of the great improvements in oils, but they should be chosen wisely. Always use a multi grade with the narrowest span of viscosity that is appropriate for the temperatures you are going to encounter. In the winter base your decision on the lowest temperature you will encounter, in the summer, the highest temperature you expect. The polymers can shear and burn forming deposits that can cause ring sticking and other problems. 10W-40 and 5W-30 require a lot of polymers(synthetics excluded) to achieve that range. This has caused problems in diesel engines, but fewer polymers are better for all engines. The wide viscosity range oils, in general, are more prone to viscosity and thermal breakdown due to the high polymer content. It is the oil that lubricates, not the additives. Oils that can do their job with the fewest additives are the best.
Viscosity Index is an empirical number indicating the rate of change in viscosity of an oil within a given temperature range. Higher numbers indicate a low change, lower numbers indicate a relatively large change. The higher the number the better. This is one major property of an oil that keeps your bearings happy. These numbers can only be compared within a viscosity range. It is not an indication of how well the oil resists thermal breakdown. "
VI and how multigrade works
To
produce a multigrade mineral oil, polymers are added to a light oil,
say SAE 20. At low temperatures the polymers are coiled up and do not
restrict the flow, but as the temperature rises they unwind so that at
100 oC (212 oF) the viscosity is equivalent to SAE 50. There is more
than one way of achieving this result. The best quality base oils have a
higher VI, which is the rate at which the oils' viscosity falls as
temperature rises within a given temperature range. This means that less
polymer is required to achieve the same result. As it's the oil that
does the lubricating, not the polymer, this is obviously preferable and
as the polymer also degrades in use the less present to start with the
better.
A good quality engine oil will have a relatively low
level of polymers and some synthetic oils have such a high VI that they
don't need any. Generally the lower the viscosity of the base oil, the
more polymer it requires. 10w-40 needs more than 20w-50 for instance,
and polymers can shear and burn, thus creating deposits which can cause
valves and piston rings to stick. A good quality oil will typically lose
up to 20% of its' viscosity in 1000 miles running, the rate of loss
then slows and the life of the oil is about 3000 miles in normal use.
I will have to agree on the polymer clarification. However, this does not mean additives are not good for engines.
Another thing to take note is that our weather is hot, but not as hot as Dubai or the deserts. There is a rule of thumb that oil runs thinner over heat. The hotter it gets the thinner it gets. Not sludge related though. If you are running on an external engine oil cooler, you can generally run a grade cooler as chances of heating up the oil isn't as high.
If you are asking be about oil clearances, please read the below.
The thinner the oil, the lower the oil pressure. The thicker the oil, the higher the oil pressure. Our bearing and bearing journals have to always be in full float when it is rotating to prevent any catastrophic damage. Sufficient oil pressure is needed for this. Not to be too thick though, as you want the oil to be able to still go through the journals. In other words,
Temperaturewise, you will be fine in regardless of any oil you use unless you are one of those who eats brake pads for lunch and revs the car like nobody's business. Try not to let the oil temperature shoot up. I've seen overheating cars with oil temperature gauges and my observation is that the oil thins out and you get to hear bearing noises the moment your engine oil goes above 120degrees Celcius, 110 in rare cases. Disaster is waiting to happen. Try to keep it at 100degrees or less. Various methods can be used to reduce your oil temp :
- External oil cooler
- Sufficient cooling system(water) to remove heat from the engine
- Wrap up the part of your exhaust that's just below the oil sump
- Good quality oil that doesn't break down over time
- Keep the engine frictionless, aka flush from time to time. Or you can use some pretty decent additives.
A good engine oil will not break down over time. Gone are the days where people run on C*****l G*x telling me that this oil is good. I want you to keep an eye on the below scenario :
"Woah!! Everytime I change engine oil, the car feels like brand new weyhh!!"
This is not good, I repeat, not good! You end users may think it is a good thing. Little did you all know is that the current oil in your engine has already broken down and stopped protecting the engine. The main three roles of an engine oil is to LUBRICATE, COOL and PROTECT. What you all should feel is that your engine does not feel any different even after your oil change. This is assurance to your conscience knowing that the oil in your engine is still doing it's job. So here, a good oil will last throughout it's recommended Oil Change Interval(OCI) whereas a normal or lousy oil will only last about two to three thousand kilometres.
Oils also have certain additives which makes them outstanding compared to their competitors. They all have normal based oils. The additives are added and blended into the oil for either that extra smoothness, performance or longevity. Two good examples will be MoS2 or ester.
- My service manual says 5,000km or 3 months, or whichever comes first. Or in other cases, 10,000km or 6 months, or whichever comes first. Why? Wanna suck my money ah?
Relax guys. Oils have very long shelf life. But one more thing that people wont tell you is that oil is hygroscopic once it's exposed to heat, or at least that's the only theory I can come up with without any lab tests done. Hygroscopic means they absorb moisture, just like brake fluids. When they absorb moisture, they lose their properties over time, hence the term "whichever comes first". 6 months probably for fully synthetic and 3 months for mineral oils. No confirmation or estimation on semi synthetics. Anything above this, there is a risk of sludge formation and oil thinning out, allowing the bearing an journals having a catastrophic intercourse.
- What oil should I use? Err... T***o oil can ah?
This section, we will divide oils into three categories once you have chosen the right viscosity for your oil.
Section 1 ~ "Performance" type of oils, Torco and motul for example. You pour these in, it feels real light and free revving, power unleashed.
Pros : As per said as the above.
Reason for Pros : Friction-reducing additives blended in. Whatever that's good for friction reduction is put into this oil.
Cons : Craps out after 1000-2000+ km, way before OCI. Feels sluggish. A little bit pricey.
Reason for Cons: These oils are so called race oils, where people use them and change them out after most or every track session. They break down fast, accelerated wear and tear.
Section 2 ~ "Normal" oil, C*****l G*x, B*r***l, L*x*s, and a few other reasonably priced oils. They are cheap, affordable, and don't give any benefit in terms of performance nor protection. Most service centres sell these.
Pros : What pros? Cheap I guess.
Reason for Pros : Cheap. For people that couldn't care less.
Cons : Long term sludge, sluggishness, "refreshed" feeling after every oil change
Reason for Cons : Cheap blend.
Section 3 ~ "Protect"ing type of oils ~ These are oils of my choice. Liqui Moly, Chemlube, Pennzoil Platinum, etc.
Pros : Long term protection, does not break down over time, not as fast as those of in Sec1 and Sec3 as per above. Very smooth and quiet
Reason for Pros : Same as S1, but more additives for long term protection is used.
Cons : May not feel as light as S1 oils. A little bit pricey. Most German oils are in this range.
Reason for Cons : Same as reasons for pros.Costwise a little bit high.
-So between S1 and S3 oils, which one should I choose?
I'd take s3. You can always choose s1 or s2, however, many cars I've seen that ran on s1 oils(OCI on time) for a long period of time end up with rattly and shaky engines. You can hear it all making noise. Cars that run on s3 oils for a long period of time(OCI on time) tend to still operate silently even after 100,000km. This is because long term protection was provided by the engine oil. Choice is yours, ball is in your court.
There are also other factors such as looking out for a good oil in terms of zinc percentage and flash point temperature which I will not elaborate. You can open the below two websites for more info :
http://www.realclassic.co.uk/techfiles/oil030319.html
http://micapeak.com/info/oiled.html
Cheers
Elton
very informative post. Thank you
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