I have seen 'scented" oils for bikes. They are the most ridiculous thing like bubble gum scent etc. I'd really like to find something you could put in the petrol to give you that old school Castor smell
Castrol R Might still be around. Check at bike shops.
Not the newer synthetic Castrol R4 stuff.
I believe I still have a case in the garden shed for when I still had my Scott Flying Squirrel.