I'm using Amsoil. Saga BLM.

Using the signature series, fully synthetic all the way

Starting from 0W-30, to 0W-40, to 10W-50, then overhaul,
then now using 0W-40.

Mileage 305000 km, 8 years car, i drive my car very hard.

I highly recommend, check it out.

Compression Loss and "1Liter engine oil loss per 5000km"  through the valve, at the 260K km mark =D

When opened engine top (head), found 4 valve seats (out of 12) badly worn off.

Had to change the whole engine top.

Foreman noted highly likely spark plugs too hot. I could agree.
Nothing to do with engine oil, everything inside the engine was pristine, except the worn valve seats.

Stock plugs are temp range 6, the platinum iridium i was using temp range 7.
Coupled with frequent sustained High Speed highway runs over the years
(consistently in excess of 160km/h, KL to Penang,Terengganu,JB),
valve seat gave way =D

Now using stock plugs, but change more often =D

FYI, on amsoil, i run 20000 (you read right: 20 thousand km) OCI =D
Agree. There no such thing as TOO GOOD of an engine oil for any engine. Depends on use case.

Filter i also use amsoil one, their EA filters, rated for the full mileage (15000 MILES or 24000KM severe duty), as per the oils.

When i need to use proton OE filters (sometimes no stock),
i will use for 10K km, then swap in another OE filter, then top up about 700ml for my car,

Then until total 20k km only change oil and filter again.