Ok , some of us have our engine oils we prefer over another type of oil , some may say Penrite is better , some may say Castrol is better etc , etc . I have no idea what my mechanic puts in my car so I'm not an oil fanboy , my question is how do you know the oil your using is better or worse than the cheapest/dearest oil , is there really any difference or is it all pumped up bulls#t . What proof do you have that your oil you swear by is better than "Brand X" ???