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A QUICK LOOK AT OIL TESTS

Today let’s look at some of the testing methods used to get unbiased data about lubricants. How does a company test its oil without slanting or influencing the results to favour its product over a competitor’s? All lubricant manufacturers use the industry standard set of tests for various operating needs of a particular oil. These have been set up and standardized by the American Society for Testing and Materials. There are tests to measure cold pour points, cold and hot viscosities, friction and wear control, gear oil film shear resistance and volatility loss. All these tests are assigned a specific test number, a specific set of steps to follow and a specific list of parameters.
It matters not whether it’s Shell, Esso, Castrol or Amsoil doing the test, it will be carried out the same way in each company’s labs.

The first test that comes to mind is testing the shear resistance of gear oil film in a hypoid gear sets of your differential. You’ve likely had a salesperson drop by your place trying to sell you their best-in-the-world oil additives they claim will do everything. The little electrically-driven machine (sometimes referred too as a one armed bandit) has a turning shaft with a bearing race on it that comes up against a stationary wear point. With levers, and in most cases weights to measure applied pressure, the salesperson shows you how their super additive makes your ordinary petroleum oil into super oil. Only one problem: the demonstrators usually use motor oil, and motor oils aren’t designed for oil film shear resistance because oil film shear forces aren’t applied to oil used for internal moving parts of an engine, transmission or hydraulic system. The machine, called a phalanx break machine, is designed solely for testing the shear resistance of gear lube oil.

In the hypoid gear set of differentials, the crown and pinion gears come together or mesh with a sliding and ripping action under severe load stresses. This action, along with heat from friction, tends to rapidly shear and degrade the lubricant and its protective film. Here again, in laboratory conditions, this test is designated a specific test number and such things as oil temperature, a specific run-in time before test pressure is applied and all the other test parameters are followed sequentially and precisely. There’s another myth blown out of the water.

With this test, you can readily see the advantages of using a top quality 2000 Series 75W90 or 75W140 gear lube in your various differentials. The two main advantages of using synthetics are: first, they reduce friction and wear, which lowers operating temperatures 20 to 30 degrees Fahrenheit and increase your equipment’s fuel efficiency. Second, synthetic lubes can be used three to six times longer than petroleum lubes. A side benefit is that the synthetic product doesn’t physically shear back in viscosity or break down into a black and grungy mess, as I’m sure you’ve seen each time you’ve drained petroleum gear lube from your differentials and planetary drives.

When synthetic additives eventually deplete to 30 per cent of new and are due to be changed, they look much like they did when installed, even though they’ve lasted up to six times longer than petroleum lubes. Synthetic lubes do not shear back or lose their high-end viscosity as petroleum products can do.

Now in motor oils and other testing for wear and lubricant film protection. Two machines are used for this. One is the phalanx journal tester with the ASTM test No. D3233. It uses a turning journal shaft running in a pressure oil bath at a designated temperature for a five-minute period.

The journal turns while under pressure from two V-blocks on either side, with pressure added little by little mechanically (that is, not by hand).

The second test apparatus is the Shell four-ball wear test, with ASTM test No. D4172. This machine tests for anti-friction and anti-wear, lube and additive capabilities, and coefficient of friction measurements. This machine has one ball rotating against three stationary balls under specific conditions of pressure, temperature, revolutions per minute and duration. At completion of each test, the wear scar size is measured on the stationary balls. For an example, a four-ball wear test of Amsoil synthetic Series 3000 5W30, Mobil 1 synthetic 5W40, Shell Rotella T 15W40 and Cummins premium blue 15W40 gave these scar sizes: Amsoil, 0.391mm; Mobil, 0.41mm; Shell,0.683mm; and Cummins,0.707mm. The lower the number, ( the smaller the scar) the better the protection.

Next is the cloud or pour point test, using a Fisher tag machine and ASTM test No. D97. This machine lowers a measured amount of lubricant to a cold temperature until the petroleum oils start to cloud. It also shows the temperature at which wax crystals start to precipitate out.

Remember, there’s no wax or varnish in synthetics. The tester then continues to lower the temperature until the lubricant, whether petroleum or synthetic, will not pour or flow. This is called its pour point, or the temperature at which the lube won’t flow.

Synthetic 15W40 motor oils have pour points as low as -45degrees C, compared to a petroleum average of -15degrees C to -30degrees C. Quite a difference when it comes to starting the ol’ tractor to blow some mid winter snow.

Another piece of test equipment used for viscosity performance is the kinematic viscosity bath tester. ASTM test No. D445 is used to test the lubes at 40degrees C and at 100degrees C. It measures the lube flow characteristics in the centistokes, or cST. The other cold performance rating machine is called a cold crank simulator, using ASTM test No.2602. this test puts the lubricant at a specific cold temperature ( this temperature depends on the lube’s viscosity rating) and measures the turning resistance of a shaft covered with lubricant.

The rating is measured in centipoises, or cP, and gives a four-digit viscosity rating. The lower the number, the lower the turning or moving resistance will be for that particular oil. As an example, Amsoil synthetic 15W40 has a rating of 2,342 cP at -15degrees C, as compared to Shell Rotella T 15W40 at 3,250 cP.

Next, we’ll look at the heat side of things. All motor oils-transmission, hydraulic and differential lubes-lose a certain amount of their volume to vapour loss at normal operating temperatures. They lose the lighter portions (molecules) of their base stock makeup, which tends to make them thicker (viscosity-wise) when cold. Here the laboratory staff uses a test called the Noack volatility test with ASTM test No. DIN 51581. The apparatus holds a container with a known weight of oil in a bath at 250 degrees C for one hour.

At the end of the test, the sample is again weighed and the resulting loss recorded as a percentage of volume loss. For example, the 15W40 synthetic product I handle has a volatility loss of 7.25 per cent, as compared to a popular petroleum 15W40 lube which has a loss of 17.01 percent. So you can see from this how synthetics save you oil and dollars because of much lower consumption losses.

Looking at engine oil consumption, keep in mind that many mechanically-related items can cause consumption problems, regardless of the oil used. These include oil leaks, worn crankshafts or camshafts bearings, misaligned con rod or wrist pin bearings, worn piston rings and cylinder parts, clogged PCV valves and breathers, wonr valve stems and guides, dirty oil and cooling systems (which put higher heat stress on lubrication), worn timing chains or out-of-time engines. All cause high vacuum and oil consumption. So, as I’ve said before, think about the over all mechanical shape of the machine which you’re thinking of changing over to synthetic lubes.

One other testing is fleet testing. Companies with commercial vehicles or heavy equipment will install synthetic lubes in a percentage of the vehicles and leaves a control group on a comparable petroleum lube and service schedule. When the test ends, all data is correlated and the information is charted.

Let’s recap some of the advantages tests have shown for using synthetic lubricants in your vehicles and equipment.

• High film strength, shear resistance and wear reduction of synthetic lubes give better fuel economy, longer wear, easier rolling and less resistance in cold weather, as well as more integrity at high loads and temperatures.
  
• Excellent viscosity and cold crank ratings of motor oils and power train lubes in the cold flow or pumpability categories make for easy winter starts and cold start wear reduction.
  
• Very low volatility rates of synthetic lubes mean, as an example, that your Cummins truck engine could run 200-plus per cent farther per quart of engine oil. Cold viscosity stays consistent longer for better starting and longer lasting oil changes. More hard earned dollars are saved.
  
• After-testing teardown of engine components show nearly factory-new cleanliness, which relates directly to longer-lasting engines. Again, many hundreds of dollars are saved with lower repair and service costs.
  
• Test after test found that synthetic lubricants reduce wear, reduce fuel costs, extend component life, reduce exhaust emissions and reduce service costs. So why would we continue using a 19th century lubricant in a 20th or 21st century equipment or vehicles.