tech

By Ryan Lee Price

On the other hand, synthetic oils are derived from a process that combines a variety of chemicals impossible to find together in nature. They are fuel-efficient, extended-life lubricants manufactured in a laboratory from select synthetic base stocks and special-purpose additives to create a custom-designed ideal lubricant. The end result is a molecular uniformity that has three basic key features: 1) Because they are produced from pure chemicals in a controlled environment, there can be no contaminants. Their fundamental purity protects them from defects and degradation brought on by contaminants; 2) Their smoother molecular structure and uniformity effectively reduce friction and provides a better level of protection over a wider operating temperature; and 3) Scientists can have customized lubricants to fulfill almost every lubricating need, even in the most demanding of conditions.

All oil must, at a minimum, protect all moving parts, reduce friction, prevent scuffing and scoring, prevent fuel from washing back down the cylinder walls, break down foaming and aeration, cool and clean the engine and disperse contaminants. Some oils do that better than others.

On the back of every can of oil there is a seal that gives you three pieces of information vital to the oil inside: the API service rating, the viscosity grade and the "energy conserving indicator." The API (American Petroleum Institute) service rating is a two-to-four-letter rating that tells you the type of engine the oil is meant for and the quality level. If the API rating (SL-CF) starts with an "S" it means the oil is rated for a gasoline engine. SA, SB, SC, SD ratings are obsolete. The only current ratings are SG, SH and SJ with SG being the lowest rating and SL being the highest. The API rating may have a dash, then a CA, CB, CC, CD or a CF rating which gives the oil a diesel engine rating. Again, CA is the lowest rating, CF is the highest. The viscosity grade (for example, 5W-30) tells you the oil's thickness, and the standard unit to measure viscosity is centistokes (cSt). An oil with too low a viscosity can lose strength at high temperatures, while an oil with too high a viscosity may not pump to the proper parts at low temperatures and the "tension" may tear at high rpms.

This is the reason for a multi-viscosity, an oil that flows freely at low temperatures but delivers protection at high temperatures. They work like this: Viscosity Index Improvers called polymers are added to a light base oil (like a 5W, 10W or 20W), which prevents the oil from thinning as it warms up. At cold temperature, these polymers are coiled up, allowing the oil to freely flow, and 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 without the polymers. The result is that at 100 degrees Celsius, the oil has thinned only as much as the higher viscosity number indicates. For example, a 20W-50 is a 20 weight oil that will not thin more than a 50 weight oil would when hot. Against popular belief, the "W" doesn't stand for weight, but for Winter.

As a general rule, always use a multi-grade oil that has the narrowest span of viscosity appropriate for your temperature zone (see chart). In the winter, base your decision on the lowest temperature you will encounter, and in the summer, the highest temperature you expect. Remember that oil with the fewest additives are the best, which is why synthetic oils perform better at a wider range of temperatures. 10W-40 and 5W-30 conventional oils require a lot of polymers to function properly at such a wide range of temperatures, leaving these two oils prone to thermal breakdown. You'll see very few experts recommending these two viscosities anymore, and even though 20W-50 has the same viscosity spread (30), it starts with a thicker base (20W) and requires less viscosity index improvers (polymers) to do the job. The synthetic oils on the market today offer superior high temperature oxidation resistance, high film strength, very low tendency to form deposits, stable viscosity base and low temperature flow characteristics. All of the conventional oils are good enough for most engines, but synthetics are superior lubricants to traditional petroleum oils. Synthetics can be run for two or three times the mileage of petroleum-based conventional oils, and they do not react to combustion and combustion by-products to the same level as conventional oils do.

There are many benefits of synthetic oils that most people do not understand, and because of their higher price, are unlikely to buy. Below are a few examples of such benefits:

Friction Reduction: This is all oils' main purposes to exist. It means a reduction in engine wear, which helps them last longer and require fewer repairs.

It also helps improve fuel economy.

Operate Cooler: Because they reduce friction, and friction equals heat, cars run cooler with synthetic oil. Cooler engines resist stress and wear, therefore lasting longer and performing better.

Thermal and Oxidative Stability: Because of their chemical composition, synthetics are inherently more stable. They offer a greater resistance to the formation of sludge, varnish, deposits and other by-products of lubricant degradation. This means engines stay cleaner, which helps them last longer and perform better.

Low Pour Point: Instead of hooking your car up to an engine heater for the night, synthetic oils offer a lower pour point, meaning that the low is less viscous, not as thick, and cold starting is much easier. For example, there are oils on the market that flow easily even at 50 below zero. This provides better protection against wear during startups because the oil can reach critical moving parts much quicker.

Wider Temperature Band: Synthetics have been produced to apply to a broad temperature range. There is better engine protection for both high and low temperatures.

Extended Life: Because most synthetic oils last longer than conventional oils, more frequent oil changes aren't as urgent as they use to be. However, any aircooled engine that has seen its share of miles should be checked frequently no matter what kind of oil you use.

Like most things involving internal combustion theory, there are people who disagree with the positive points of synthetic oil, and there are a several misconceptions still floating around the aircooled community. The following are several letters from VWT readers who have the wrong idea about synthetic oil:

Jim Nichols, of Riverside, Calif., writes: "...and the seals are shot, but I blame my oil for that. It's synthetic and I heard they wear away seals." Jim, this can't possibly be the problem. What oil manufacturer would create an product that isn't compatible with seals? However, the composition of seals are a problem that conventional oils as well as synthetic oils must overcome, as they are made from elastomers (basically a polyvinyl) and is difficult to standardize.

Elisha Miller, of West Ossipee, N.H., in a letter about high temperature problems with his '76 Transporter, states: "All of the synthetic oils seem too thin to stay in my engine, as I can't get the engine's temperature normal and it leaks more now than ever." Elisha, in order for any oil to be classified in any SAE (Society of Automotive Engineers) grade (10W-30, 10W-40, etc.) it has to be within certain guidelines in regards to viscosity. It makes no difference whether it's 10W-40 conventional or 10W-40 synthetic, at minus-25 degrees and 100-degrees Celsius, the oil has to maintain a certain viscosity or it can't be rated a 10W-40. You should get that leak fixed regardless of what kind of oil you use, but at lower temps, synthetic oil is thinner and prone to leak.

Jose Rodriguez, of Las Cruces, N.M., writes, "...and I've been tempted to switch back to petroleum oil because it burns through a quart of synthetic in about two weeks." One of the active ingredients of synthetic oil are molecules that lower the coefficient of friction. Basically, it is what makes oil slippery. If your engine leaked (and what VW doesn't?), it is possible that it would leak a little more because of this chemical. However, if you engine is sound, oil consumption will actually be reduced because of a synthetic's lower volatility and because of the better sealing characteristics between pistons rings and cylinder walls. As well, synthetics have antioxidants, small suicidal martyrs that are consumed by oxygen at high temperatures instead of the oil.

Jim Richards, of Hollendale Beach, Fla., who normally uses synthetic oils in both his Manx-style buggy as well as his '73 Super Beetle, asks: "My engine was down a quart, and all I had was some regular oil. I'm worried that I may have damaged my engine by mixing synthetic oil with regular oil. Is there a rebuild in my future?" No Jim, your engine's fine. Maybe years ago you would have been in trouble, when synthetics were new and companies used untested ingredients that were not compatible with other oils, but those days are long behind us. According to the experts at Mobil, synthesized hydrocarbons, polyalphaolefins, diesters and other materials that form the base stock of name-brand synthetics are fully compatible with conventional oils. However, a note of caution: Whether using conventional or synthetic oils, you should use the same brand and rating oil to top off your fluids that are currently in your car. The functions and additives blended for specific characteristics can be offset when oils with different additive mixtures are put together. Though it may not be especially damaging to your engine or its parts, it certainly doesn't help things.

Francis "Frosty" Jones, of Punxsutawney, Penn., shares about a routine oil change. "When I dropped the mesh filter, it was clogged with sludge like molasses. I had four quarts of synthetic next to me, but I heard that it would be worse." In fact, "Frosty,"synthetics are more sludge resistant than conventional oils, resisting the effects of combining high temperatures and oxygen. When engine temperature reaches it maximum, two things happen: First, the lighter ingredients which give an oil its fluidity (viscosity) boil off, making the oil thicker. Second, many of the complex chemicals found naturally in petroleum-based oil, plus manufacturer-produced additives, begin to react with each other, forming sludge, varnishes and gums. The result is a loss of viscosity at lower temperatures, which is essential to get the oil to vital parts when first starting the engine. Other negative effects of thickening oil include the restriction of oil flow into critical areas, greater wear on moving parts and loss of fuel economy. Because of their higher flash points and their ability to withstand evaporation and oxidation, synthetics are much more resistant to sludge development. (Another cause of sludge is the introduction of dirt into the fuel system, but this is more of a problem with the air filter than the oil).

Oil Additives--Do or Do Not?

Synthetic oil companies have gone to great lengths to develop an oil package that meets most vehicle requirements for a wide variety of temperatures and climates, and a lot of these oils have chemicals in them that are synergistic, meaning that they work better together than separate. If you add anything to these oils, you may upset the balance and prevent the oil from performing its job. To fight a wide variety of engine problems, turn to fixing the engine rather than fixing the oil.

What Oil is Best for You, a Comparison

The commercial shows oil being boiled in a saucepan over incredible heat and it still flows smoother than the "leading brand." Another one drains the oil out of an engine to show how protecting it is even when it isn't there. It's hype, like most mass-media advertising. They get your attention and then they sell you the product. You don't get to hear about viscosity indexes, flash and pour points, sulfated ash or zinc content, the six most important properties all motor oils available to the public. These properties are collectively referred to as "typical inspection data." The chart below compares, by weight, a variety of oils on the market today

·Viscosity Index: This is an empirical number indicating the rate of change in viscosity of an oil within a given temperature range. The SAE (Society of Automotive Engineers) assigns certain numbers to certain ratings based on a variety of testing procedures. Higher numbers indicate a low change, while lower numbers indicate a large change. The higher the number the better, as you bearings will be happy, but this is not an indication of how well the oil resists thermal breakdown.

·Flash Point: In degrees Fahrenheit, the flash point is the temperature at which an oil gives off vapors that can be ignited by a flame. The lower the flash point, the greater tendency for the oil to suffer vaporization loss at high temperatures and to burn off on hot cylinder walls and pistons. Flash point indicates quality of oil, and the higher the better.

·Pour point: Also measured in degrees Fahrenheit, the pour point is five degrees F above the point at which a chilled oil shows no movement at the surface for five seconds when inclined. This is especially important for oils used in winter climates, and the lower the better. In addition to a pour point, a borderline pumping temperature is given by some manufactures, which is a temperature at which the oil will still pump and maintain adequate pressure. This is roughly 20 degrees above the pour point.

·Sulfated Ash Content: The percent of sulfated ash is how much solid material is left over after the oil burns. A high ash content will form more deposits and sludge in the engine, while a low ash content promotes longer valve life.

·Zinc Content: Zinc is used in oils as an anti-wear additive, and will only be present in oils that are used when there is actual metal-to-metal contact in the engine. The zinc compounds react with the metal to prevent scuffing and wear. Under normal use, a level of 0.11 percent is sufficient enough to protect an engine for the entire oil-drain interval. Higher zinc content doesn't give you more or better protection, it gives you longer protection, but the downside is that a high zinc percentage can lead to deposit formations and plug fouling.

Side-By-Side Comarison
Brand	V.I.	Flash	Pour	%ash	%zinc
20W-50
AMSOIL	136	482	-38	0.5	n/a
Castrol GTX	122	440	-15	0.85	0.12
Exxon High Performance	119	419	-13	0.70	0.11
Havoline Formula 3	125	465	-30	1.0	n/a
Kendall GT-1	129	390	-25	1.0	0.16
Pennzoil GT Perf.	120	460	-10	0.9	n/a
Quaker State Dlx.	155	430	-25	0.9	n/a
Red Line	150	503	-49	n/a	n/a
Shell Truck Guard	130	450	-15	1.0	0.15
Spectro Golden 4	174	440	-35	n/a	0.15
Spectro Golden M.G.	174	440	-35	n/a	0.13
Unocal	121	432	-11	0.74	0.12
Valvoline All Climate	125	430	-10	1.0	0.11
Valvoline Turbo	140	440	-10	0.99	0.13
Valvoline Race	140	425	-10	1.2	0.20
Valvoline Synthetic	146	465	-40	1.5	0.12
20W-40
Castrol Multi-Grade	110	440	-15	0.85	0.12
Quaker State	121	415	-15	0.9	n/a
15W-50
Chevron	204	415	-18	0.96	0.11
Mobil 1	170	470	-55	n/a	n/a
Mystic JT8	144	420	-20	1.7	0.15
Red Line	152	503	-49	n/a	n/a
5W-40
Havoline	170	450	-40	1.4	n/a
15W-40
AMSOIL	135	460	-38	<0.5	n/a
Castrol	134	415	-15	1.3	0.14
Chevron Delo	400	136	421	-27	1.0	n/a
Exxon XD3	n/a	417	-11	0.9	0.14
Exxon XD3 Extra	135	399	-11	0.95	0.13
Kendall GT-1	135	410	-25	1.0	0.16
Mystic JT8	142	440	-20	1.7	0.15
Red Line	149	495	-40	n/a	n/a
Shell Rotella w/XLA	146	410	-25	1.0	0.13
Valvoline All Fleet	140	n/a	-10	1.0	0.15
Valvoline Turbo	140	420	-10	0.99	0.13
Brand	V.I.	Flash	Pour	%ash	%zinc
10W-30
AMSOIL	142	480	-70	0.5	n/a
Castrol GTX	140	415	-33	0.85	0.12
Chevron Supreme	150	401	-26	0.96	0.11
Exxon Superflo Hi Perf	135	392	-22	0.70	0.11
Exxon Superflo Supreme	133	400	-31	0.85	0.13
Havoline Formula 3	139	430	-30	1.0	n/a
Kendall GT-1	139	390	-25	1.0	0.16
Mobil 1	160	450	-65	n/a	n/a
Pennzoil PLZ Turbo	140	410	-27	1.0	n/a
Quaker State	156	410	-30	0.9	n/a
Red Line	139	475	-40	n/a	n/a
Shell Fire and Ice	155	410	-35	0.9	0.12
Shell Super 2000 155	410	-35	1.0	0.13
Shell Truck Guard	155	405	-35	1.0	0.15
Spectro Golden M.G.	175	405	-40	n/a	n/a
Unocal Super	153	428	-33	0.92	0.12
Valvoline All Climate	130	410	-26	1.0	0.11
Valvoline Turbo	135	410	-26	0.99	0.13
Valvoline Race	130	410	-26	1.2	0.20
Valvoline Synthetic	140	450	-40	1.5	0.12
5W-30
AMSOIL	168	480	-76	0.5	n/a
Castrol GTX	156	400	-35	0.80	0.12
Chevron Supreme	202	354	-46	0.96	0.11
Chevron Supreme Synt.	165	446	-72	1.1	0.12
Exxon Superflow HP	148	392	-22	0.70	0.11
Havoline Formula 3	158	420	-40	1.0	n/a
Mobil 1	165	445	-65	n/a	n/a
Mystic JT8	161	390	-25	0.95	0.1
Quaker State	165	405	-35	0.9	n/a
Red Line		151	455	-49	n/a	n/a
Shell Fire and Ice	167	405	-35	0.9	0.12
Unocal		151	414	-33	0.81	0.12
Valvoline All Climate	135	405	-40	1.0	0.11
Valvoline Turbo		158	405	-40	0.99	0.13
Valvoline Synthetic	160	435	-40	<1.5	0.12
5W-50
Castrol Syntec	180	437	-45	1.2	0.10
Quaker State Synquest	173	457	-76	n/a	n/a
Pennzoil Performax	176	n/a	-69	n/a	n/a

A Quick Reference Guide to Oil Choices
Engine Oil		Outside Temperature (*F)
SAE Viscosity	-20	0	20	40	60	80	100
20W-20	no	no		yes	yes	yes	yes		yes
20W-40	no	no		yes	yes	yes	yes	yes
20W-50	no	no		yes	yes	yes	yes		yes
10W-30	no	yes	yes	yes	yes	yes	yes
10W-40	no	yes	yes	yes	yes	yes	yes
10W	no	yes	yes	yes	yes	no	no
5W-30	yes	yes	yes	yes	yes	no	no
5W-20	yes	yes	no	no	no	no	no

A Quick Reference Guide to Oil Choices
Engine Oil		Outside Temperature (*F)
SAE Viscosity	-20	0	20	40	60	80	100
20W-20	no	no		yes	yes	yes	yes		yes
20W-40	no	no		yes	yes	yes	yes	yes
20W-50	no	no		yes	yes	yes	yes		yes
10W-30	no	yes	yes	yes	yes	yes	yes
10W-40	no	yes	yes	yes	yes	yes	yes
10W	no	yes	yes	yes	yes	no	no
5W-30	yes	yes	yes	yes	yes	no	no
5W-20	yes	yes	no	no	no	no	no