Originally Posted by
Slaninar
The reason I use it is because when changing motor oil, there is always some left in a bottle - which is enough to last a long time.
Also, last time I was looking for some oil, SAE90 and 20w60 cost both around 4 $ per litre.
Both 20w60 and SAE90 are the same as far as bicycle chain lubing goes - whichever one can find cheaper, or more convenient.
I think good advice is to use
whatever motor oil is on hand,
whatever the viscosity, and a good inexpensive source is the residue remaining in the packaging container of whatever oil is used when changing motor oil for any motorized vehicle.