Historically boutique motorcycle oils have been weak in detergent for expecting short oil drain intervals. Lack of detergent keeps the oil prettier, longer, in the engine. Many have been aghast at how black Rotella-T turns almost immediately after using exotic boutique motorcycle oils. Rotella was only cleaning up the junk the others left behind. The multiuse diesel/gasoline Rotella-T has lots of detergent for black diesel soot.I used Motul 7000 a coupla times. Expensive but I was leaving it in the bike for a longer than normal trip. Ester added, and that perty red dye. Is not ester synthetic, and wouldn't it be reasonable to assume the oil makers have to have some content of synthetic esters. If it says synthetic on the label, have we been lied to all these years?
Amsoil is one of the 3 or 4 who make synthetic base oil. Mobil, Total, probably Shell, one of the Swedish companies, and Amsoil. Possibly Bel-Ray and other little guys. Not Castrol who has always been a blender not a refiner or manufacturer.I use Amzoil synthetic a lot..... what have I been paying for? Who makes Amzoil's oil anyway?
Sadly, Amsoil really does make exceptional motor oil but is sullied by Amway-derived marketing.
Marketeers control the US Department of Commerce and the same in every other country. You might note how direct comparison of motor oil products is forbidden in advertising. Years ago some barely got around this by claiming "Motor oil C did this, and motor oil P did that!" thinly disguising the manufacturers. Manufacturers can only claim to "meet or exceed" industry specifications. Can not directly claim their product is better than another. Marketing works very hard to make the consumer's imagination believe things that were not really said.
Amsoil's heavily marketed failure "Lifetime Oil Change" of about 30 years ago used a no-detergent oil which always stayed pretty honey colored in the mistaken belief an exotic oil filter would capture all the crud. Didn't work. The oil stayed in spec as claimed but the engines sludged to the point of failure. "Dirty" motor oil is good. It means the crud is coming out with the drain and not staying inside the engine. Motor oil does not make the discoloration, it collects it from combustion blowby.