Yes, under 'harsh' driving conditions ang conditions dito sa atin. But a good mineral-based oil can take it. Yes, you may get some benefits from synthetic, but the cost difference is still not justifiable (at least by my wallet's standard).

Synthetic oils will keep their lubricating properties longer. But the primary reason we change the oil is not because the oil has 'broken down'. Rather it is because there are already contaminants suspended in the oil (because of the cleaning effect of the oil). That's why changing oil every 5k kms is better for me because I get to throw out the contaminants more often. And since mineral oil does not lose its lubricating properties in the span of 5K kms, I just use mineral. Tipid pa.