Hello,
As a owner - you should ensure that the RC is been transferred in new owner name on immediate and priority basis
Else - without transfer - if there is some road accident or an illegal activity been done - cops will first approach the original owner of the vehicle and may turn out to be hassle in proving that the vehicle has been sold
When New Owner intending to Transfer
> Assist Owner in getting the New NOC
> If possible and the new owner is busy - hire a mediator agent and share in 50% - 50% cost - so that he can collect documents and proceed for submission of documents in RTO for RC Transfer
When New Owner not Co-operating in Transfer
> Send him reminders and may record conversation on call and save in your online storage
> If possible - send him registered post reminders and keep copy with you with dates for effecting transfer
In event of vehicle not transferred in next 3 months or you suspect foul play - may register a police complaint suspecting illegal activity as the new owner not transferring vehicle in his name by show in proof of correspondence, recorded conversation, sale transfer forms as sign and still new owner not transferring vehicle in his name and you suspect illegal activity due to same
Hope should help !!