Need na ma overhaul yung engine?

[SkyFlakes88]

i have been filling oil to the mark for decades now.. no issues, either.

now, why don't the car manufacturers recommend this "slight underfilling" if it is as beneficial as some entities say?
devil's advocate here..

Kasi po yun ang full capacity nang engine nila. Kung 4liters e d ilalagay nila 4 liters syempre sir. Whether your oil level is at just above minimum up to full. Your engine can run without any problems. But kung just above the min.level sa dipstick you can use the cars just don't rev it to it's limits until you are at least 3/4 from full.