3 years ago

MOTOREX Magazine 2008 85 EN

  • Text
  • Motorex
  • Hydraulic
  • Motor
  • Alpine
  • Ariete
  • Oils
  • Technical
  • Engines
  • Ortho
  • Viscosity

M o t o r o i l M o t o

M o t o r o i l M o t o r o i l The use of renewable components in diesel fuel, subject of much discussion around the world, has a significant effect on the properties of motor oils. A MOTOREX study reveals some very interesting results. Dyn. viscosity at 40 °C [mPas] 300 250 200 150 100 50 Increase in dynamic viscosity (Test at 150 °C and 30 l of air per hour) A 223 168 172 C B D 121 95 E F 102 Current study: biodiesel and motor oil Rapid, precise analysis saves time and enhances the productivity of the well equipped MOTOREX-labs. Innovations in diesel engine technology continually set new challenges for motor oil. In response to the EURO 4/5 emission standards and use of modern exhaust gas post-treatment systems, MOTOREX has developed a new additive technology for lowSAPS motor oils low in ash and sulfur. In recent years the use of unsaturated vegetable oils such as rapeseed oil methylester has begun to affect lubricant properties. Many engine producers have responded by recommending more frequent oil changes. Analyzing samples provided by customers, MOTOREX’s tribology specialists saw a need for action and started a study. Unsaturated fat acid triglyceride molecule: healthy for people, hazardous for engines. Dangerous molecules Due to their much higher flash points, natural oils and fats such as rapeseed oil, sunflower oil, castor oil and the like do not burn as well as diesel fuel. If the engine fails to reach the optimum operating temperature, unburned components condense on the cylinder walls. These residues are carried into the motor oil by the piston rings. Depending on the application and engine condition, MOTOREX chemists have found concentrations of up to 40% of dangerous vegetable molecules (triglycerides) in the lubricant by the end of the prescribed oil change interval! Why are triglycerides dangerous? These molecules contain several atoms with double bonds, with two atoms in a tug-of-war for the same pair of electrons. Double bonds are unstable and easily broken, leading to oxidation and the formation of long-chain molecules (polymerization). This rapidly increases the viscosity of the motor oil, boosting sludge formation and thickening the oil. Stray electrons that form insoluble chemical compounds are even more hazardous, leading to deposits on sensitive engine parts and clogging filters and lubrication holes. Tests in the lab and on the road How do engines, biodiesel and lubricant react in the test tube and on the road? A mixture of diesel and rapeseed oil was used to find out. Different high-tech motor oil formulas of the same viscosity (SAE 10W/40) were used for each test. In a lab test at 150°C with plenty of oxygen (30 l of air per hour), viscosity was found to remain constant for a certain time and then rise exponentially. Following analysis of the results, the particularly well-balanced MOTOREX FOCUS 4 SAE 10W/40 formula was chosen for the field test. 484,557 km in the driver’s seat The fleet test started in April 2006 with the help of a trucking company. Five Mercedes- Benz ® trucks were driven nearly 500,000 kilometers using the following three fuel mixtures: • diesel fuel with 5% rapeseed oil • a mixture of 55% rapeseed oil and 45% kerosene • 100% rapeseed oil An oil sample was taken every 5,000 km and analyzed in the lab. The oil was changed 0 h 72 96 120 144 168 192 216 240 264 288 312 336 360 8 9 Time of test With motor oils A and B, viscosity rose sharply in as little as 170 hours. Product C was at the middle of the pack while D and E proved strong competitors. Formula F, MOTOREX FOCUS 4, came out on top, with constant viscosity for well over 300 hours. using MOTOREX FOCUS 4 SAE 10W/40 at intervals depending on the results of the analysis. For several of the vehicles it was possible to maintain the standard 50,000 km interval, although a significant concentration of rapeseed oil was found. An oil change was recommended once this concentration exceeded 15%. The fleet test furnished clear confirmation of the results previously obtained in the laboratory. Exciting findings The study made it possible to identify and outline the different chemical reaction models. The effect of the optimum operating temperature was especially noteworthy. Engines that generally ran too cool (idling, numerous cold starts, short distances) saw relatively high levels of contamination with the renewable fuels. It was particularly striking how the extended field tests corroborated the experimental lab results. The tests also identified the best-suited motor oil for our customers. In testing and practical use, MOTOREX FOCUS 4 SAE 10W/40 is the clear winner. For any questions about this subject please contact your MOTOREX partner. Five vehicles were used for the field test and kept under constant observation. A technician takes an oil sample. Various engine parameters were measured and scrutinized after the test runs. Soot contamination levels were normal.



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