AOA Fellows, wanted to share my experience regarding opting the engine oil for your cars.
some members claimed that boiling or flash point of all 5w-30 is also 230 Celcius so higher temperatures dont matter to minerals or synthetics or 5w-30 is as protective as 5w-40 or 5w-50.
let me clarify that's not the case.
race cars use atleast 5w-60 oils. why?? because they actually operate on a higher strains on the engine components and operating temp is higher. the actual measure of weights in the oils is viscosity index at a specific temp.
usually road cars operate at 100 degree celcius so if you see that the viscosity index of higher viscosity 50 weight oils is better at 100 degree celcius as compared to 40 or 30 or for that matter 20 weight oils.
viscosity index is actually the ability of the oil to stick to metal parts at operating temperature ( in simple words) of the engine. so 5w-50 is more protective. i hope i have clarified this.
now when we talk about mineral and synthetic oils the main difference is that synthetics maintain their specific properties over longer interval where as mineral based oils usually loose their properties sooner.
now if we are using 10-30 mineral it would be fine. no issues at all if you follow the maintenance routine religiously.
opting for mineral 10-30 would mean lower operating costs and thats the advantage. however if you intend to run the car optimally for lets say 300K KMs than safer approach would be to opt for synthetic 5w-50 specially if u have a heavy foot and u floor the car frequently.
now opting for imported synthetics is still safer like shell grey box ultra 5w-40, liqui moly 5w-40, i personally use micking max premium 5w-50 (in my vitz), mobil 5w-50 or petronas 5w-50 and would IA opt for taglon 5w-50 from toyota dealership for corolla when the change interval is reached.
have not heard good review about kixx oils however its a hear say thing so they might be good too or total 7000 /9000.
so opt intelligently. drive safe. happy crusing.