hold onto or hold on to?
I've looked up this phrasal verb and found that 'hold on to' means the same as cling to (or grab) something, to continue to keep possession of something;
but I don't know when I have to use this expression correctly in a sentence and also wonder if the right way to write(and use) it is 'hold onto' or 'hold on to'.

For example, If I want to tell someone not to give up an opportunity in her/his life ( like a job she/he has just got), can I say:

''Hold on to this job opportunity. Don't ever let go of it!''
or
Hold onto this job opportunity. Don't ever let go of it

so if someone knows about that, please explain this to me. Thanks in advance.

Question

hold onto or hold on to?
I've looked up this phrasal verb and found that 'hold on to' means the same as cling to (or grab) something, to continue to keep possession of something; 
but I don't know when I have to use this expression correctly in a sentence and also wonder if the right way to write(and use) it is 'hold onto' or 'hold on to'.

For example, If I want to tell someone not to give up an opportunity in her/his life ( like a job she/he has just got), can I say:

''Hold on to this job opportunity. Don't ever let go of it!''
or
 Hold onto this job opportunity. Don't ever let go of it

so if someone knows about that, please explain this to me. Thanks in advance.

Answer

This is actually a very good question. Basically, both of those usages are the same. There isn't a grammatical difference between "onto" and "on to" when you put the word "hold" in front of it.

Now, if you use other types of words with "onto" or "on to," it will make a difference. In this case though, native speakers and writers use both of those phrases interchangeably.