@Kamundu,
When you say light,what is light?Oil grading is done in relation to type and viscosity......In a layman's term,viscosity is the resistance to flow.....The higher the number,the "thicker"(More resistant it is to flow).It follows therefore that any liquid/oil rated 30 has the same flow resistance
What i am trying to explain is that a Guiness of 30W,convetional oil of 30W and a synthetic oil of 30W have the same viscosity.The difference in the three will be in other properties and the purposes they are intended for.Let's eliminate Guiness since we know that it is a preserve of throats.I will not dwell on the superiority of synthetic but it is a simple scientic fact.
@Mlefu,
There is no known car manufacturer who recommends servicing of cars basing on days/months/years and the reason is simple.Suppose you service your car and keep it in a garage for the entire 12 months,would you require another service despite not using the car thereafter?.Most equipments are serviced based on hours/mileage and thus your oil is rated in Kms.
As for European cars,different models and where they were sold have their own parameters.If you import a Merc from Japan,you would find that for it to conform to the recommended 8K Kms service,DT Dobie would need to do some reconfigurations on your service memory....and Yep,most Mercs are sericed every 8K kms (Minor service) and 30K kms (Major service).The same should apply to BMW,VW and Audi.
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