Even if they gave you a gift of €140,000, it would have no immediate tax implications, assuming that you had not received large gifts before.
Your parents could gift you up to €225,000 and it would be exempt from CAT.
In theory, Revenue could argue that you are getting an annual gift of around €9,000 a year, the value of the interest. The first €3,000 is exempt anyway. So you would be accumulating €6,000 a year towards your €225k exemption.
So, I suspect that if you repay the loan over time, it's unlikely to be of any interest to the Revenue.
If your parents subsequently make a gift to you, you could then ask the local Revenue office if you need to declare the notional gifts in the past.
What is more important is that you do actually put the terms of the loan in writing. I have seen cases where people have subsequently claimed that this loan was actually a gift. Merely noting in writing that it is a loan, that it is interest-free and repayable, is good practice.
If your parents were to die before the loan is paid off, the executor might claim that the repayments were simply payments of interest and that the full amount is still outstanding.