Previously I was using Castrol fully synthetic and my engine was consuming engine oil and tappet sound was obvious. I went to my mechanic to open up the top head and seal back with their glue, also seal some part that we suspect was causing the leak.

The best engine oil on the shelf that time was Amoil so I have to take it. The result was surprisingly good. Engine is not consuming engine oil anymore, tappet sound was gone and engine is smooth. Just maybe needs a bit more effort to revv to higher rpm.

So I was wondering...should I stick to this Amoil engine oil? (It is B3/B4 rated)

yes, it is amoil..not the famous amsoil. I have a bottle of liqui moly and 1 can of ceratec ready, so in case I find out this oil might causing potential trouble to my 4age engine, I would immediately change it.

Google it up and found its website. This oil is made in Malaysia. 

"Amoil (Malaysia) Sdn Bhd was established in 1996 and has been engaged in the business of manufacturing and marketing high quality petroleum products for top brands from the United States of America and across the globe into the Malaysia."