To help fill the never-ending search for knowledge which is USENET:-}, the following info sheet (FAQ if you wish) is being posted to rec.motorcycles and rec.autos.tech monthly. Any updated information would be greatly appreciated.
Current Author: Tom Coradeschi
E-Mail: tcora@pica.army.mil
Original Author: Ed Hackett
E-Mail: edh@maxey.unr.edu
NOTE: Status of Tom Coradeschi's WEB page:
"All of Tom Coradeschi's personal stuff has been removed from this site. Absolutely no further information is available on it."
Edits:
v1.0 First there was 1.0. Before that there was darkness.
v1.1 Change in description of viscosity.
v1.2 Updated info on AMSOIL (courtesy of Morgan McArthur <mgn@inel.gov>)
A TEXT copy of the most current oil_facts can be found at URL: http://skylands.ibmwr.org/tomk/sbr/tom/tech/oil_facts.html (R)
Oil companies provide data on their oils most often referred to as "typical inspection data". This is an average of the actual physical and a few common chemical properties of their oils. This information is available to the public through their distributors or by writing or calling the company directly. I have compiled a list of the most popular, premium oils so that a ready comparison can be made. If your favorite oil is not on the list get the data from the distributor and use what I have as a data base.
This article is going to look at six of the most important properties of a motor oil readily available to the public: viscosity, viscosity index (VI), flash point, pour point, % sulfated ash, and % zinc.
The weights given on oils are arbitrary numbers assigned by the S.A.E. (Society of Automotive Engineers). These numbers correspond to "real" viscosity, as measured by several accepted techniques. These measurements are taken at specific temperatures. Oils that fall into a certain range are designated 5, 10, 20, 30, 40, 50 by the S.A.E. The W means the oil meets specifications for viscosity at 0 F and is therefore suitable for Winter use.
The following chart shows the relationship of "real" viscosity to their S.A.E. assigned numbers. The relationship of gear oils to engine oils is also shown.
_______________________________________________________________
| |
| SAE Gear Viscosity Number |
| ________________________________________________________ |
| |75W |80W |85W| 90 | 140 | |
| |____|_____|___|______________|________________________| |
| |
| SAE Crank Case Viscosity Number |
| ____________________________ |
| |10| 20 | 30 | 40 | 50 | |
| |__|_____|____|_____|______| |
______________________________________________________________
2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42
viscosity cSt @ 100 degrees C
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.
Very few manufactures recommend 10W-40 any more, and some threaten to void warranties if it is used. It was not included in this article for that reason. 20W-50 is the same 30 point spread, but because it starts with a heavier base it requires less viscosity index improvers (polymers) to do the job. AMSOIL can formulate their 10W-30 and 15W-40 with no viscosity index improvers but uses some in the 10W-40 and 5W-30. Mobil 1 uses no viscosity improvers in their 5W-30, and I assume the new 10W-30. Follow your manufacturer's recommendations as to which weights are appropriate for your vehicle.
Pour point is 5 degrees F above the point at which a chilled oil shows no movement at the surface for 5 seconds when inclined. This measurement is especially important for oils used in the winter. A borderline pumping temperature is given by some manufacturers. This is the temperature at which the oil will pump and maintain adequate oil pressure. This was not given by a lot of the manufacturers, but seems to be about 20 degrees F above the pour point. The lower the pour point the better. Pour point is in degrees F.
Brand VI Flash Pour %ash %zinc ====================== === ===== ==== ==== ===== 20W-50 AMSOIL (old) 136 482 -38 <.5 --- AMSOIL (new) 157 507 -44 --- --- Castrol GTX 122 440 -15 .85 .12 Exxon High Performance 119 419 -13 .70 .11 Havoline Formula 3 125 465 -30 1.0 --- Kendall GT-1 129 390 -25 1.0 .16 Pennzoil GT Perf. 120 460 -10 .90 --- Quaker State Dlx. 155 430 -25 .90 --- Red Line 150 503 -49 --- --- Shell Truck Guard 130 450 -15 1.0 .15 Spectro Golden 4 174 440 -35 --- .15 Spectro Golden M.G. 174 440 -35 --- .13 Unocal 121 432 -11 .74 .12 Valvoline All Climate 125 430 -10 1.0 .11 Valvoline Turbo 140 440 -10 .99 .13 Valvoline Race 140 425 -10 1.2 .20 Valvoline Synthetic 146 465 -40 <1.5 .12 20W-40 AMSOIL 124 500 -49 --- --- Castrol Multi-Grade 110 440 -15 .85 .12 Quaker State 121 415 -15 .90 --- 15W-50 Chevron 204 415 -18 .96 .11 Mobil 1 170 470 -55 --- --- Mystic JT8 144 420 -20 1.7 .15 Red Line 152 503 -49 --- --- 5W-50 Castrol Syntec 180 437 -45 1.2 .10 Quaker State Synquest 173 457 -76 --- --- Pennzoil Performax 176 --- -69 --- --- 5W-40 Havoline 170 450 -40 1.4 --- 15W-40 AMSOIL (old) 135 460 -38 <.5 --- AMSOIL (new) 164 462 -49 --- --- Castrol 134 415 -15 1.3 .14 Chevron Delo 400 136 421 -27 1.0 --- Exxon XD3 --- 417 -11 .90 .14 Exxon XD3 Extra 135 399 -11 .95 .13 Kendall GT-1 135 410 -25 1.0 .16 Mystic JT8 142 440 -20 1.7 .15 Red Line 149 495 -40 --- --- Shell Rotella w/XLA 146 410 -25 1.0 .13 Valvoline All Fleet 140 --- -10 1.0 .15 Valvoline Turbo 140 420 -10 .99 .13 10W-30 AMSOIL (old) 142 480 -70 <.5 --- AMSOIL (new) 162 520 -76 --- --- Castrol GTX 140 415 -33 .85 .12 Chevron Supreme 150 401 -26 .96 .11 Exxon Superflo Hi Perf 135 392 -22 .70 .11 Exxon Superflo Supreme 133 400 -31 .85 .13 Havoline Formula 3 139 430 -30 1.0 --- Kendall GT-1 139 390 -25 1.0 .16 Mobil 1 160 450 -65 --- --- Pennzoil PLZ Turbo 140 410 -27 1.0 --- Quaker State 156 410 -30 .90 --- Red Line 139 475 -40 --- --- Shell Fire and Ice 155 410 -35 .90 .12 Shell Super 2000 155 410 -35 1.0 .13 Shell Truck Guard 155 405 -35 1.0 .15 Spectro Golden M.G. 175 405 -40 --- --- Unocal Super 153 428 -33 .92 .12 Valvoline All Climate 130 410 -26 1.0 .11 Valvoline Turbo 135 410 -26 .99 .13 Valvoline Race 130 410 -26 1.2 .20 Valvoline Synthetic 140 450 -40 <1.5 .12 5W-30 AMSOIL (old) 168 480 -76 <.5 --- AMSOIL (new) 186 464 -76 --- --- Castrol GTX 156 400 -35 .80 .12 Chevron Supreme 202? 354 -46 .96 .11 Chevron Supreme Synt. 165 446 -72 1.1 .12 Exxon Superflow HP 148 392 -22 .70 .11 Havoline Formula 3 158 420 -40 1.0 --- Mobil 1 165 445 -65 --- --- Mystic JT8 161 390 -25 .95 .1 Quaker State 165 405 -35 .90 --- Red Line 151 455 -49 --- --- Shell Fire and Ice 167 405 -35 .90 .12 Unocal 151 414 -33 .81 .12 Valvoline All Climate 135 405 -40 1.0 .11 Valvoline Turbo 158 405 -40 .99 .13 Valvoline Synthetic 160 435 -40 <1.5 .12
The synthetics offer the only truly significant differences, due to their superior high temperature oxidation resistance, high film strength, very low tendency to form deposits, stable viscosity base, and low temperature flow characteristics. Synthetics are superior lubricants compared to traditional petroleum oils. You will have to decide if their high cost is justified in your application.
The extended oil drain intervals given by the vehicle manufacturers (typically 7500 miles) and synthetic oil companies (up to 25,000 miles) are for what is called normal service. Normal service is defined as the engine at normal operating temperature, at highway speeds, and in a dust free environment. Stop and go, city driving, trips of less than 10 miles, or extreme heat or cold puts the oil change interval into the severe service category, which is 3000 miles for most vehicles. Synthetics can be run two to three times the mileage of petroleum oils with no problems. They do not react to combustion and combustion by-products to the extent that the dead dinosaur juice does. The longer drain intervals possible help take the bite out of the higher cost of the synthetics. If your car or bike is still under warranty you will have to stick to the recommended drain intervals. These are set for petroleum oils and the manufacturers make no official allowance for the use of synthetics.
The numbers above are not, by any means, all there is to determining what makes a top quality oil. The exact base stock used, the type, quality, and quantity of additives used are very important. The given data combined with the manufacturer's claims, your personal experience, and the reputation of the oil among others who use it should help you make an informed choice.