|09-29-2012, 04:00 PM||#1|
Oil info thread
What's in your motor oil?
Base Oils (the origins of conventional/mineral and synthetic oils)
Constituting 80-90% of the finished motor oil, the base oil(s) play a very important role. The structure and stability of the base oils dictate the flow characteristics of the oil and the temperature range in which it can operate, as well as many other vital properties such as volatility, lubricity, and cleanliness. The two major categories of base oils are Mineral Oils and Synthetics.
Mineral oils begin with crude oil, a mixture of literally hundreds of different molecules derived from the decomposition of prehistoric plant and animal life. The lighter more volatile components of crude oil are stripped away to make gasoline and other fuels, and the heaviest components are used in asphalt and tar. It’s the middle cuts that have the right thickness or viscosity for lubricants, but first they must be cleaned up; undesirable components such as waxes, unsaturated hydrocarbons, and nitrogen and sulfur compounds must be removed. Modern processing techniques do a pretty good job of removing these undesirable components, good enough for well over 90% of the world’s lubricant applications, but they cannot remove all of the bad actors. And it’s these residual “weak links” that limit the capabilities of mineral oils, usually by triggering breakdown reactions at high temperatures or freezing up when cold. These inherent weaknesses limit the temperature range in which mineral oils can be used and shorten the useful life of the finished lubricant.
Mineral oils are further subdivided into three subgroups (Group I, Group II, Group III) that differ by the degree of processing they undergo. Higher groups have been subjected to hydrotreating or cracking to open aromatic (ringed) molecules, eliminate unstable double bonds, and remove other undesirables. This extra treating yields water-white clear liquid with higher VIs, enhanced oxidative stability, and lower volatility.
Group IIIs are a somewhat controversial class as they are derived from crude oil like Groups I & II, but their molecules have been so changed by severe processing that they are marketed as Synthetics. Most people now accept Group IIIs as synthetic, but the discussion remains heated among purists, and I’m going to duck by not taking a side here.
Synthetic base oils are manufactured by man from relatively pure and simple chemical building blocks, which are then reacted together or synthesized into new, larger molecules. The resulting synthetic basestock consists only of the preselected molecules and has no undesirable weak links that inhibit performance. This ability to preselect or design specific ideal molecules tailored for a given job, and then create those molecules and only those molecules, opens a whole new world for making superior basestocks for lubricants. In fact, the entire formulation approach is different: instead of trying to clean up a naturally occurring chemical soup to acceptable levels with a constant eye on cost, the synthetic chemist is able to focus on optimum performance in a specific application with the knowledge that he can build the necessary molecules to achieve it. And since full synthetic oils are generally a company’s premier offering, their best foot forward so to speak, the additives are often better and in higher doses as performance trumps cost.
In general, synthetic base oils offer higher oxidative and thermal stability, lower pour points, lower volatility, higher VI, higher flash points, higher lubricity, better fuel economy, and better engine cleanliness. The amount and balance of these improvements vary by synthetic type, and can be quite significant for the engine and user.
There are many types of synthetic base oils, the most common being Polyalphaolefins (PAOs), Esters, Alkylated Naphthenes (ANs), and more recently Group IIIs. These different types of synthetic base oils are often blended together (or even with mineral oils), to give the balance of properties desired. All offer improved performance, but at a higher price, which brings up the question of value – how much performance to you need, and how much should you pay for it?
For the average car owner, driving conditions are mild enough for conventional mineral oils to work satisfactorily, provided they are changed relatively frequently (5,000-7500 miles). For those users with high performance engines, severe climates, hard driving, or utilizing long drain intervals, synthetics can offer good value and may even be required. And then there are those who so love their cars that nothing but the very best will do for their baby.
So, as you can see, modern motor oils are very simple mixtures of very complex ingredients. Choosing the right components of the right chemistry in the right dosages is a real balancing act, as each of the components have their own pluses and minuses and can interact or compete with each other. Don’t try this at home – leave it to companies you trust who have the technology, R&D, and resources to achieve the necessary balance so critical to performance.
Last edited by Big Black Boss; 09-29-2012 at 09:08 PM..
|09-29-2012, 04:16 PM||#2|
Differences between Groups I through V oil basestocks
Motor oil is a mixture of base oil and an additive package. The base oil can be from any of five groups, or mixtures of these groups, as long as the finished product meets the spec on the package label. Here are the groups:
Group I base stocks contain less than 90 percent saturates and/or greater than 0.03 percent sulfur and have viscosity index greater than or equal to 80 and less than 120.
Group II base stocks contain greater than or equal to 90 percent saturates and less than or equal to 0.03 percent sulfur and have viscosity index greater than or equal to 80 and less than 120.
Group III base stocks contain greater than or equal to 90 percent saturates and less than or equal to 0.03 percent sulfur and have viscosity index greater than or equal to 120.
Group IV base stocks are polyalphaolefins (PAO).
Group V base stocks (esters) include all other base stocks not included in groups I, II, III or IV.
Base oils in Group III, Group IV, and Group V have the legal right to be marketed as "synthetic." That is a marketing term, not necessarily a technical term.
After reading about the different oil basestock groups and the previous post above, "What's in your motor oil", go to this:
Motor Oil University - Motor Oil 101 <--There's a midterm and final exam at the end of the ten chapters.
Everything should start making sense by now. Please see the two threads below.
1. Myth between synthetic and regular (conventional/dino/mineral) oil for daily drivers
2. Oil analyses from various Club RSXers
Last edited by Big Black Boss; 09-29-2012 at 04:47 PM..
|09-29-2012, 09:14 PM||#3|
What's the best oil to use?
Taken directly from bobistheoilguy.com (BITOG):
Looking for an oil recommendation? The BITOG community would love to help you find a good oil for YOUR vehicle and YOUR habits. Sometimes we can also help you find an oil to address a problem you might be having, such as oil consumption. Here's how to make a post that will help us zero in on your best option.
First, remember one thing:
There is no "best" oil!
This question comes up frequently. Everyone has their own personal favorites, but there's no such thing as a one-size-fits-all oil, or a best oil "overall". Every engine is different. Every oil has its place. What works for one engine might not work for another.
So, when you ask for advice, tell us about your car! The more details, the better. Here are the essential points:
1. What kind of vehicle you have
2. What your owner's manual says -- not just viscosity, but certifications (look for acronyms like API SM, ILSAC GF-4, etc.) and change intervals as well
3. Where you live
4. How you drive (easy? hard? fast? slow?)
5. What your daily drive is like (short trips? long trips? city? highway?)
6. Whether your car has any known problems
If you have any preferences -- synthetic vs. conventional, store-bought vs. ordered online, how long you'd like to go between oil changes, etc. -- or any other info you think might be important, let us know that as well.
Once again, the more details, the better. BITOG loves a good oil recommendation thread, especially when you give us a lot to work with.
|info , oil|