Please Use any clean gear oil, if not available, use some engine oil but do not use grease, as it add more dust and sand in the chain and sprokets, resulting early damaging of both,, I have faced it already. Although WD40 is a unique item but this removes colours,paints and leave some shades on surfaces,
So Oil is the best solution.
1 lakh ki Motorcycle bana li par Chain cover teen wala cheap,,Agar chain covers k nuts ko ziyda tight kia tho slip,,oops,, One of my friend have A sport bike and its chain covers are Superb made from shiny Aluminium.
Shame on our famous (so called) brands