Engine Oil in itself is a formulation of oil and additives to give it certain characteristics. All oils do lubrication but to enhance it additives are added. These additives are derived from petroleum itself and also from other chemicals.
Why I chose LM specific oil is that it has reduced oil consumption at 2000 km from 300ml to non existent. On dip stick I used to see 2cm drop but now I see only 0.25 cm drop which I would call non existent. LM Super leichtlauf is working dear as advertised. They say it has seal conditioners and what I observed confirms it.
Now the additive part. This additive is MOS2 (Molybdenum Di-sulphide) an old well known heavy duty lubricant. Among oils different additives are used to enhance its lubrication properties, a few of these use MOS2. LM is one of them and makes oil called MOS2 Leichtlauf which is already prepared mixture of oil and MOS2 and you do not need to add more MOS2 in it. The oil I have chosen suits old engines with high mileage does not have MOS2 in it rather other conventional lubrication related additives. To increase its lubrication properties you have formulation in your own hands at least a little of it. What bad would it be if you have an option to Custom setup your oil characteristics? I think its best option. MoS2 has an industrial background and is a proven compound so my confidence is on it. Secondly LM itself is a respected name worldwide so more power to LM and to my confidence
About oil viscosity, 20 and 50 do not mean they are meant for ambient/atmospheric Temperatures of 20 and 50 degrees C or F. They are weights of oil that have a corresponding range of Temperature degrees that they can accommodate to with respect to their RATE of Flow & Density of oil layer. Where the first number 20 is the weight of oil on ambient temperature/or cold engine. The later number 50 is the weight of oil on working temperature of engine/warmed up under load state e.g in 10w40 weight 10 can bear a little below Zero degree C and would still flow on a cold engine upon starting the car. As soon as the car warms up it temperature would reach 85+ degrees the other part of oil weight 40 will come in effect. 40 serves well up and beyond 50 degree C and still providing enough flow and density. Kindly check the Viscosity chart for clearance over internet.
10w40 is the most suitable thickness of oil with respect to flow and density at all temperature that Cuore engine requires. You increase the viscosity you increase your engine drag and drop your mileage and response from throttle. You decrease the viscosity you give a hard time to your valves, guides, springs and cam shaft and rest about every other moving part inside engine.