Posts by Zish and Borris are right and there reasonings are also precise but what I was trying to say is same but sorry that I failed to convey it rightly.
Anyways Borris has already suggested the optimum oil for the poster whereas Zish has explained harmful effects of low grade oil.
but for sure to keep up a healthy discussion I would like to justify my points and post above.
Oil pressure is an important thing which is somehow very important to heavy engines but I think in smaller cars we should not worry about the fact. I am petroleum engineer and I have experimented lubricant pressure wrt engine performance and here is an explanation which may make you understand what I actually wanted to convey.
Oil pressure must be sufficient enough to ensure that the rotating components within the engine ll not contact with each other hence no wear to the components. Viscosity is something on which all scenerio of oil pressure studies stands. Optimum viscosity is desired, oil neither be too much viscous nor too less.. to much viscous oil also cause excessive load and engine heatup..
its true that manufacturer always recommend marginal oil grade to be used we can use higher grade for better performance but grade should not be higher to extent that it ll cause harm ..and the grade borris told is actually right for the poster and effects of using low grade oil is explained by Zish.
regarding oil change I am sorry ranges provided above was based on my way of driving so I am regretfull i usually drive at highways due to my job nature thts why i use to change oil frequently othervise running within city doesnt require so frequent oil changes.
I have always practiced to change my filter after every 6000 km and i found it ryt thts why i wrote above.
no offenses to anyone and I apologize if I have delievered some wrong info. but what i tried to explain is some what borris and zish delivered.
