Yes, I’ve run into that too. Do people really think that Ford or John Deere actually make the oil themselves?
Actually, all of that is one of the reasons why standards setting organizations like the SAE, IEEE and the DIN in Germany are so useful. If a given product meets a certain SAE or DIN standard - then that is all you need to know. People who swear that this oil or that brand of electrical tape is crap make me smile…..because there is no logical basis on which they could form such an opinion.
It’s like people who believe that skinny b!tch Gwyneth Paltrow knows more about nutrition, immunology and public health than medical authorities all over the world.
Lots to say about that ... And has been said.
I remember end 60 ies When pushrods for Brit bikes was in the Press .. " Pirate Parts " they were called
Having a tendency to bend and causing .engine failure
The Standardization sticker DIN or so is just a sticker on the bottle .Who knows what is inside And sometimes these can be minimum requirements.
I had Motul in a Honda Fireblade ..and when changing went for a Autosuppliers Oil that had the Specification sticker should be fine.
But warm days after a faster ride it rattled at low rpm ...so I did not dare to keep it in the bike I am economical and don't do it unless I feel it necessary. It is subjective to some extent but I do tune Guitars so I believe I have reasonable ear. Impression was that the " Snake Oil " did not have as good high temperature capability
Replaced it with some known Oil company's brand and the high temp rattle disappeared.
Dont remember what company .. But I stick to those Known brands that has been around a long time Valvoline / Castrol / Perhaps Shell
And I stick to the exact specification according to vehicle manufacturer unless engine is worn.
They are a bit more Expensive ,,but thats how I do it.
Sadly there are tricksters out there at booth ends ..The OEM companies can order Oil from fex Castrol and increase price with a factor 3x and having their own sticker on the Bottle the same oil as in Castrol's bottles.
At the other end perhaps up to spec min requirements with lesser additives that are cheaper and not so good
Other factors are Clutch that in XS 650 can slip for some Oils
Riding style
Warm up before setting off
How often changing oil some manufacturers prescribes Oil changes after a trip around the block
It is not them that pays especially if it is the same manufacturers oil that is the " Only " one you can use
Bordering to Fraud.
How worn is the motor perhaps going for a slightly thicker oil in an older engine which can be dangerous