The introduction of regulations or standards meant of course, also testing. Actually one can divide these into three groups: 1. Chemical testing, which perhaps doesn't really say anything about how much of each substance is present, but which provides, e.g., evidence concerning acidity and oxidisation. 2. Physical testing. You may have heard about this one. The oil runs through a glass viscometer, where the typical spherical form in the middle can be seen. Either that, or a metal object is drawn across an oil-smeared surface. 3. Stress-testing of the oil in the engine. What, e.g., do the components look like after a certain number of kilometers?
To 1: Here, e.g., the presence of metals in the oil can be indicated. Here you can watch a small clip about flame spectroscopy. To test the acidity you may remember the Litmus-test from your schooldays, this is used to determine the acidic value. The further the ph-values drop below 7, the higher the acid content in the engine oil is. Nowadays, using the emission spectroscopy, this is done much faster, more precisely and reaches almost into the area of atoms.
To put it more simply, one irradiates the substance to be tested with laser-light, then analyses the resulting spectrum. By the way, all these chemical tests are of course, carried out on the oils already being tested. One is given, e.g., through the metals present, an exact impression of the amount of wear and tear, even without spending 1000 or more hours testing.
To 2: The above described test to determine the transit-time, may well be suitable for technical instruction. These steel balls (see above) are also available for the counters of car dealers, they are simulations of the falling-ball-vicosimeter by Höppler. The developments in the direction of automated measuring operations will go beyond this this.
The standard nowadays, are the fully-automatic functioning viscosimeters, which work together with, e.g., a Windows-PC. Engine oil temperatures of between -40°C to 150°C must be able to be set. With one measuring station 2 samples per hour can be evaluated. In a specialist laboratory there are probably devices which have several measuring stations and automatic rinsing after each test. Nowadays, even in this field the rationalisation is obvious.
To 3: The actual checking in the engine can be complemented by specially contrived equipment, whereby, a defined friction force can be applied to a friction pairing and the abrasion surface can be measured. However, real test-bench trials, where sometimes even a non-functional engine is mounted, give far more usable information.
The Caterpillar company is probably one of the top companys who have provided outstanding service as far as this, third type of oil-testing is concerned. In 1920, General Motors also had a laboratory, where also the testing of engine oil was part of the road test. In this case, the dismantling after a certain running performance and strain, is about the simplest test.
In the course of these workings, the first genuine oil-standardization emerged, which was christened 'Heavy Duty'. It required a higher additive content and was intended for both petrol- and Diesel engines which had to do their job under severe conditions. The most important requirement of this standard, also valid today, was that all oils must be mixable with each other. So, don't let anyone tell you that you can't mix XXX oil with YYY oil. Indeed, the properties of the two oils are shared according to the proportions they represent.
As an additional example we've embedded a video-clip, where the possible performance increase through a change-over to synthetic oil, is measured. 11/11