Ok Zulfiqar, here I put one example.
In Pak. still the majority is consuming 20/50 (in old, medium & even new engines) and keep the change interval as 3~4K max.
Now, more than 100 times I've seen that when somebody comes to change oil after driving 3K, the oil is "almost freaking dead". Just put 2 drops on finger tip and rub is gently. The lubrication is near to zero and oil feels like "Grece".
Now when somebody come after using 3.5~4K PTT Performa oil, then at-least its in "Oil state" who still have lubrication.
That is the reason make me hate to these local oil companies (shell, Caltex, total, pso, Toyota, Suzuki, Honda, etc.) Their 20/50 is not a new oil. Just something refined and re-packed again in bottles. That’s all.
Hence for local oils who are coming like Greece, how we can expect that oil filter will work well?
Synthetic oils are quite thinner and keeps engine happy & healthy. Hence oil filters can keep its good functionality till 5~6K even.