Not all.... I don't even use even single part which is a replacement or alternative on my Nissan b14 or my Suzuki liana.I always use genuine and oem parts .. Both are 1.8L and using liquimoly 5w30 on them since a pretty long time... And we've had experiences with all types of oil used by clients...
We've seen the engines using liquimoly oils and the other using these three locally available oils.
And I did my compression last 1.5years ago. 180 in each cylinder. And was outta budget so never changed the oil...
Pulled it out, oil was obviously dirty but, dirty brown not black like diesel oils,... Kher got it flushed twice... Engine is super clean. And still the compression is same 180psi.
So I've done many rebuilds and lifted head of many different oil brand users. So I would not convince you to use amsoil, liquimoly or mobil since its your pocket, and your will... But I'd say these are some world recognised brands, even if they're not available in Pakistan, they're high quality stuff...
If you can't afford something and you have never used it so you can't make biased judgement or your review, claiming them as lies or liars...
Now people come to me, I simply ask them there choice of oil, since many clients trust different oils. So we don't force them, we just guide them, if they are willing we order the lubes and get the work done...
So take my suggestion, to judge something you need to check both extremes... Like cheap to cheapest and expensive to expensive most.. And then you can make a judgment or a claim..
No harshness to anyone. Just keeping my point of view upfront.