A film of engine oil on metal surfaces affords lubrication (reduces metal against metal friction) also convects away heat away from hot engine parts. With a detergent in the oil, it also cleans and inhibits corrosion. There are two broad kinds of engine oil: Mineral oil (petroleum based) and Synthetic (read expensive and high performance).
In cold countries, people don't go above 20-weight oil. But even 20-weight is too high for starting an engine in freezing atmospheric temperatures. Then you need 0-weight or 5-weight.
By blending a polymeric viscosity index improver, the oil can behave as 5-weight oil when cold and 20-weight oil when hot. This is called a multigrade 5W20 oil.
In India we don't go above 40-weight. In Bhopal/Nagpur like temperature extremes 10W40 is a good multigrade oil to use.
2fast4u, as ambient temperatures rise, engine operating temperatures rise too.
Assuming you are driving in the hot middle-eastern desert conditions, you need the 50-weight oil to protect your engine from heavy wear.
The more viscous the oil you use, the more silent your engine will run. Of course it will encounter more continuous resistance and be more fuel-inefficient. And higher viscosity oil is not necessarily good for the engine. The oil won't flow through all the engine's oil passages swiftly and properly. While it might quieten the engine, it wont lubricate it properly and long term there will be more wear and tear.
There are commercial friction reducing additives you can use. These are usually a colloid of a very fine, exceptionally slippery substance -- Molybdenum Disulphide, Polytetrafluoroethylene (PTFE)[DuPont's Teflon and the Australian Nulon-E30], ZX1 and Active8 are anti-friction agents. Mfrs claim these agents reduce wear by 'bonding' to the bearing surfaces filling in surface imperfections.
Studying the automotive used-car market in the US in the 1980s, I learned that while selling an old car, there was an unethical practice that cheats would use. They would dump a big bagful of graphite-powder into the engine oil, temporarily increasing its viscosity so that it would run quiet long enough for a buyer to be hoodwinked into buying it.
Ram |