1972 house with 174 sqm from the neighborhood

Yes, you can: (also leaving out the word age and retirement): 60,000 loan from the parents, interest-free, … you also pay 500€ monthly, and that for 10 years. Or how long should the parents wait for their money? … I don't care, but it has to be mentioned.

That depends on the age of the parents and how much money they have otherwise. For a 27-year-old, they may very well still be working and then perhaps still have enough money for the first years of retirement.

It depends on the age of the parents and how much money they have otherwise. At 27, they could very well still be working and then might still have enough money for the ersten Rentenjahre.

And what about the rest? Or is it assumed that they only live to be 70 years old? What if they want to retire early? The OP has to know how far to use the parents' money.

It's about the fact that the OP has to manage with €3000. And that doesn't work if the parents lend the money. It only works if they gift it. €3000 is not a cornucopia and an interest-free loan is not a grab bag.

You are acting as if you were unbuttoning your parents' last shirt again. We don't even know that. And even if that were the case, as long as there is money left over, it wouldn't matter. The parents will surely build up more reserves again, so with a bit of luck the loan could gradually turn into a gift.

And what about the rest? Or is it assumed that they only live 70 years?

No, of course not. But by then, with only 200 euros repayment and a term of 25 years, they will have paid it off. Or after 20 years with the appropriate repayment. You have to spread private retirement provision over the years of average life expectancy anyway. And then you just take the loan for the last years.

You all act as if one is taking the last shirt off the parents' backs again. We don't even know that. And even if so, as long as there is money left over, it wouldn't matter. The parents will surely build up further reserves again, so that with luck the loan could gradually turn into a gift.

No one can forbid the OP. There are just different opinions; as is usual in forums; about accepting money from the parents, when they have already supported and financed the child for at least 20 years.