First 4 or 5 oil changes I used conventional oil - no particular brand.
Tried semi-synthetic blend for a few changes after that.
Now using full synthetic usually - no particular brand - whatever is available, and/or on sale, but have gone back to conventional a couple of times. Sometimes add Lucas oil treatment (usually when I've gone "back" to conventional oil). Engine has never been "flushed" to this point.
Oil filter is a "no name" brand, carried by a bunch of auto parts stores/suppliers - but is made by Honeywell.
Oil and filter changed like clockwork, every 5,000 km/~3,000 miles - doesn't get too dirty with that mileage, and I don't mind performing the frequent changes (done myself) - still doesn't burn a drop of oil between changes, no leaks.
Vehicle approaching 300,000 km/~190,000 original miles and still going.
IMO, it's probably more important to change the oil and filter frequently and regularly - more so than the particular type/brand of oil used - they all seem to meet the minimum standards for any particular grade (API standards) - haven't noticed any appreciable performance "differences" using conventional vs. synthetic - though synthetic doesn't seem to "change" colour (get as "dark/dirty") as easily between changes.