Is all lying considered to be 'unwholesome'? Suppose I tell a lie in order to protect others or to protect myself; is it still considered to be 'unwholesome'?

Or let's take the common example of a person who isn't really moral; is it okay to inform friends/colleagues of this aspects, or is it unkind to the person?
Sutta. Ma. Ma. cūḷarāhulovādasuttaṃ:

&quot;In the same way, Rahula, when anyone feels no shame in telling a deliberate lie, there is no evil, I tell you, he will not do. Thus, Rahula, you should train yourself, 'I will not tell a deliberate lie even in jest.'

The four noble truth is the opposite of lying.
It's a reason that I super trust in Pali Canons because the Noble Ones can't lie at all situations.
Although I am an ordinary, I can the witness that it is possible to speak the truth in all situations because I never lie through 12 years in Buddhism. It depends on personnal management. Actually, there has not only the lie method, so the practitioner should practice the other methods instead of the lie.
However, the noble one has at least three methods to manage the unsecured situation by the murder, etc.

Running away.
Asking the evaded question to let the listeners think of the answer by themselves. See Dha.A.4 sahassavaggavaṇṇanā Tambadathikacoraghatakavatthu.
Mute. or sacrifice his life to keep the truth. It's just mute until the murder tortures or kills the noble one. See Dha.A.5 pāpavaggavaṇṇanā Maṇikārakulupakatissattheravatthu.

The ordinary thinks lying is the only way, but the noble one thinks there are many ways instead of the lying to manage the unsecured situation.
Additional
In Khuddaka.A. (paramatthajo.) Sikkhāpadavaṇṇanā:
How is big of the fault from the lie?

In immoral animals, e.g. ant and chimpanzee,  lie the small body is lesser fault than bigger because of it's required more effort to lie if both animals can understand the lie.
In moral animals, e.g. human and god, lie the lower wholesome skill is lesser fault than higher.
In the animal which has the same body and wholesome skill, lie the higher passion is more fault than the lower.

All Ariyas Can't Lie
In Sutta. Aṅ. (2): catukkanipāto Āpattibhayavaggo VoharaSutta:

250. Expressions (1st)
250. Paṭhamavohārasutta
“Mendicants, there are these four ignoble expressions (the noble one doesn't express).
“Cattārome, bhikkhave, anariyavohārā.
What four?
Katame cattāro?
Saying you’ve seen, heard, thought, or known something, but you haven’t.
Adiṭṭhe diṭṭhavāditā, asute sutavāditā, amute mutavāditā, aviññāte viññātavāditā—
These are the four ignoble expressions.”
ime kho, bhikkhave, cattāro anariyavohārā”ti.
251. Expressions (2nd)
251. Dutiyavohārasutta
“Mendicants, there are these four noble expressions. (the noble one expresses).
“Cattārome, bhikkhave, ariyavohārā.
What four?
Katame cattāro?
Saying you haven’t seen, heard, thought, or known something, and you haven’t.
Adiṭṭhe adiṭṭhavāditā, asute asutavāditā, amute amutavāditā, aviññāte aviññātavāditā—
These are the four noble expressions.”
ime kho, bhikkhave, cattāro ariyavohārā”ti.
252. Expressions (3rd)
252. Tatiyavohārasutta
“Mendicants, there are these four ignoble expressions.
“Cattārome, bhikkhave, anariyavohārā.
What four?
Katame cattāro?
Saying you haven’t seen, heard, thought, or known something, and you have.
Diṭṭhe adiṭṭhavāditā, sute asutavāditā, mute amutavāditā, viññāte aviññātavāditā—
These are the four ignoble expressions.”
ime kho, bhikkhave, cattāro anariyavohārā”ti.
253. Expressions (4th)
253. Catutthavohārasutta
“Mendicants, there are these four noble expressions.
“Cattārome, bhikkhave, ariyavohārā.
What four?
Katame cattāro?
Saying you’ve seen, heard, thought, or known something, and you have.
Diṭṭhe diṭṭhavāditā, sute sutavāditā, mute mutavāditā, viññāte viññātavāditā—
These are the four noble expressions.”
ime kho, bhikkhave, cattāro ariyavohārā”ti.