I'm scared a.f. to make a mistake there 
So should i convert my privkey to WIF or it is WIF by standard?
It's easy to determine if it's WIF. So should i convert my privkey to WIF or it is WIF by standard?If it starts with '5' and consisting of 51 base58 characters, then it's WIF.
If it starts with 'L' or 'K' consisting of 52 base58 characters, then it's also WIF but flagged for compressed public keys.
If it's not, tell us how many characters it has and only the first character.
Quote from: Zipp_1199
I'm scared a.f. to make a mistake there
When importing the private key to an offline Bitcoin Core, you're just basically copying it to that offline wallet.dat so it's quite safe. Mistakes are bad when "sweeping" a private key since it'll directly send all of the associate funds to the new wallet.