Mystery of W
In this blog, I want to go over a few related topics. First, I want to answer what “W” stands for in oil type. Then, I want to go over how they are categorized and their effectiveness.
Ever wonder what “W” stands for on an oil label, like 10W-30? Let me change up the question. If I ask you, “what does ‘W’ stand for on an oil label,” how will you answer? More often than not, the “W” is mistaken for “weight.” Weight for oil, as most commonly thought. In fact, we receive many inquiries regarding if Polytron MTC will mix with “10 weight oil” and such. Admittedly, I, too, am guilty for using such phrases, as it is so commonly used in the general public and, of course, doesn’t the “Weight” start with a “W” anyways? Let’s go over how oil types are classified.
Short Answer: W stands for Winter
“W” stands for “winter.” When oil grades are hyphenated (i.e. 10W-30), this indicates range of viscosity attainable with this particular oil, namely it behaves like 10 weight oil (less viscous) when it is cold or “winter” and thanks to viscosity modifiers (manufacturer added oil additives), it will behave like 30 weight oil (more viscous) when hot.
Continuing the discussion from short answer above, Society of Automotive Engineers, or SAE, has successfully deployed motor oil grading system, which we all use universally. The confusion of using “weight” all started from SAE J300 designation rules for single-grade oil. Often, single-grade oil is used in industrial applications where temperature does not vary significantly or for specialty uses, including certain classic cars, air compressors, and lawnmowers. According to the definition SAE J300, there are 11 single-grade oil types available: 0W, 5W, 10W, 15W, 20W, 25W, 20, 30, 40, 50, and 60. All the numerical values are correctly referred to as “weight” or “straight-weight” oils. It is correct to say 20 weight oil for 20; 5W shall be called 5 weight winter-grade oil. Yes, that W remains “winter” no matter what.
So what is the difference between single-grade and multi-grade oil? Single-grade oil worked great when the application did not demand for wide temperature ranges, like cars. An engine from an automobile will see extreme temperature change. If you live in Kodiak, Alaska, and start your car, the engine may be at -30F, so is the motor oil inside. When you drive down to a store, thanks to thermostat and combustion heating, the engine might warm to 180F, so does the oil inside. That is 210F change in temperature! As you can see, if single-grade oil was used in such application that was designed to perform only at -30F, engine will likely to seize or detrimental wear could occur at 210F, and vice versa, assuming no Polytron MTC oil additive has been applied.
Multi-grade is then, simply, advanced motor oil that can transform the viscosity depending on the operating temperature to most optimally run your engine. You would want low viscosity (easy to flow, like water) when you are cold, and higher viscosity (hard to flow, like honey) when you are hot. The effect of such abilities come from specialized polymer additives called Viscosity Index Improvers (VIIs), added at motor oil manufacturer. Note that viscosity of different grades varies logarithmic with temperature, that is, change in viscosity is 10 times more than change in temperature. This is getting bit too long now, so I will stop here. Well, with little more fun stuff!
- It is possible to make multi-grade oil without VIIs. If this happens, it is allowed to be sold as either single-grade extremes, such as 20W-20 without VII, can be sold as 20W single-grade or 20 weight single-grade.
- Motor oil grades are NOT same as gear and axle oil grades! SAE J306 defines the gear oil grades differently, and therefore higher number oils, like 75W-140, does not imply it is more viscous than motor oil because they are on different scales!
- Polytron MTC is premixed with 10W-30; one of the most common motor oil to mix efficiently with your main oil. We also produces Full-synthetic and Semi-synthetic motor oil with Polytron mixed in.
Wankel Rotary Engine Invention
We thought of a good topic for you: Mathematics! Actually, I don’t want to scare you right off the bat, so I want to explain what this is about. One of the most interesting alternative to conventional internal combustion engine design is the Wankel Rotary Engines, or Rotary engines in short. Felix Wankel, a German Engineer, invented the first Wankel engine in 1957, after 7 years of development. They are 4-stroke engines without piston and crankshaft, but rather, it uses mathematically defined rotor and housing, and eccentric shaft that replaces crankshaft. Please view the video below to see how they work:
Rotary Engine Mathematics
I know this is amazing. But how does the rotor keep a tight contact between the sides against the wall of the housing? Is that a triangle in a oval housing? Well, answer comes from math. Yes, it’s all MATH!
There is a well known math function called epitrochoid. This defines the basic shape of the rotor housing.
That being said, the general resulting function can be seen as this (from Wikipedia):
So, does that remind you of anything? YES, the Wankel engine!
Mazda RX Series – Rotary Engine to the Next Level
Wankel engine design has been incorporated into many different industries, but Mazda, a Japanese auto manufacturer, has taken Rotary Engine to a whole new level. If you have heard of Mazda RX-7, a very high performance car with twin-rotor rotary twin-turbo engine, well now you know how to design that engine. Mazda RX-8 took the same design and improved to produce 240HP from 1.3L displacement engine. One thing to note here is that unlike regular reciprocating piston engines that completes a whole cycle in 720 degrees, Rotary engines does this in 1080 degrees, which can be counted against them. 1.3L is also not fully “true” or comparable to reciprocating engine. More details on Wikipedia and other auto-related sources. Due to motion of eccentric shaft, it is OK to compare 1.3L Rotary engine with 2.6L piston engine. Though, Rotary engines do have higher volumetric efficiency and minimal pumping losses.
Now, this is the ultimate Wankel Rotary Engine car: Mazda 787B Le Mans Race Car. I personally saw this car during Mazda Owner’s Car Show in Irvine area, Orange Country, Calif. This is one gorgeous car!! Comes packed with Quad-Rotor (four Rotary engines) and capable of 930HP (690kW) at ~9000rpm.
Even with Rotary Engines, Polytron Oil Additive will perform well and will prolong the life of your engine. Use Polytron MTC in the lubrication system, and use Polytron Fuel Conditioner (GDFC) in the fuel to get best performance out of your Rotary Engine.
For more information regarding Wankel Rotary Engines, see:
Learn About Automotive Differential
This is a tutorial video of how an automotive differential or the “rear-end” works in your car. Very thorough and easy to understand. This seemingly simple device is the key component to distribute torque to your wheels. There are different types of automotive differentials: spools, locking differentials, limited slip differentials (LSD), and open differential. The list is in order of more locking to less locking.
Types of Automotive Differential
A type of automotive differential called the spools are used almost exclusively in racing/offroad. Spools will not allow torque differentiation, meaning no matter what, both wheels will rotate at the same rate. This can give a great advantage in offroading condition, such as severe duty and racing, and drag racing. By guaranteeing equal distribution of torque to both wheels, you can now see why racers would like to have such device. If it’s so good, why not have it on regular cars, you may ask. Well, if you cannot differentiate the rotation, you are essentially stuck going straight. Only way for you to turn is to have inner wheel slip (chirping tire and burning rubber) because it travels less when making a turn.
A locking differential is usually heavy duty device that allows you to lock manually. Many have electric switch to engage or disengage the lock. When you lock it, it will act like a spool, the non-differential automotive differential we talked about. This is more common in offroad vehicles, like 4×4 trucks because you can lock at your command when you need the traction.
Limited Slip Differentials (LSD):
An LSD is like an automatic locking differential. These are more common in road race cars and higher end automotive differentials. The operation is simple in concept. The locking portion is really never a full lock but rather, it is operated by friction of some sort like spring and wet clutch, and this allows slippage to prescribed degree when you need to turn and will “lock” when you need the traction. One way to tell if your vehicle has LSD or not, you can jack your car up and rotate the one wheel. If your other wheel rotates in the same direction, then you have an LSD. Another way to test is to perform a burn-out and if both tires lose traction (rubber mark), then you have an LSD, but please do not perform this unless you are completely safe and perform this test at your own risk.
An open differential is the most basic form of automotive differential system as described in the video. This will transmit torque to the easiest path. What I mean is, if one of your wheel is in dirt and another on asphalt and if you try to accelerate quickly, the wheel in the dirt is the only wheel that spins and the wheel on the asphalt remains stationary. Similarly, if you try to burn-out with an open diff, only one wheel will leave the tire mark. This is the most common of all and is the one in your vehicle, unless you drive a sporty car.
I decided to share this information with you because I just changed my 2002 Camaro Z28’s differential oil. Of course, I added Polytron MTC in, the best automotive differential fluid additive, but no more than 6oz since the capacity of my differential is 1.75-2qt. The car runs quieter than before and I feel much more comfortable knowing that my ring-pinion and LSD set will last me for a very long time with Polytron Metal Treatment Concentrate, most advanced oil additive.