Aoa guys. I just want to know one thing. I have corolla 2012 gli 50,000 kn driven. Engine is in very good condition. Initailly i used caltex 20w-50 oil for 2 years or so and then switched to shell hx7 5w-30. Engine is doing good. But today a mechanic said that this oil is not is not good as its viscocity is not for the engine and it is depositing sluge in the engine. I fail to undertsand this as shell is a good oil and i buy it from panj sarki company operated pump.I want to know if this shell oil is of bad quality.
He said its good to use toyota 5w-50 new toyota oil. Where as in car manual the oil grade mentioned are 5w-30, 10w-30,15w-40 and 20w-50. So using 5w-50 shell or toyota new oil in white plastic bottle would be good option? These both are fully synthetic oils? Please suggest.