Jungling Olaf is a very moderate speed jungle but olaf is amazing at keeping atleast 1/2 health in his rotation. If there is anything you would like to tell me to help me please feel free but this is just what i do. If you wanna try things dif go for it.

I use very Mix mash runes. This is b/c olaf works best for me with these runes.

reds:
5 armor pen
4 attack dmg

Yellow:
4 armor
5 attack speed

Blue:
9 magic resit.

Quint:
1 Health
2 Armor pen

I use these to keep him alive in jungle as well as ganks.

These masteries are my usual ones for olaf that help him become a dominating character. Again u can change these up for your team or for you.

This is a weird build i tweaked for most matches.
Start like most jungles with 5 health pots and a cloth armor

at first back go into madrids razors then Zerker greaves. if needed pick up more health pots.

build madrid's into wriggle's lantern then build a phage then build it into Frozen Mallet.

After that u can change up the build depending on the team but i prefer to build starks to keep up the jungle and for the team.

Next build an atmos for obvious damage armor and some crit.
Lastly i build a warmogs to make olaf into an unmovable brick ****house!

with this build u top out at
4.5k health
1k mana
200 armor
60 magic resist
200 damage.

If this build isnt your olaf style or they make their team high magic dmg then id advise switching your Wrigles at the end of the game into Wits end, Guardian Angel, or force of nature.

This is what i tested and found out that makes the best and most sustained full game.

For this jungle, start with some1 leading blue. From blues go straight to wolves--->wraiths--->Golems----> Red buff---> wolves--->wraiths--->gank or golems.
Go back after a gank or golems.
buy as much of the items as u can and atleast 1 potion if not 3 max
then go back and get redo the rotation ganking when needed or taking lanes.
If you get counter ganked or die you can figure out what is needed. Get ur jungle warded.

Pros:
-his jungle is very strong
-he is medium speed in jungle but very hard to counter jungle b/c of his passive. this helps him by poping ur W wich is a life steal nuke that destroys others.
-Olaf is a good counter jungler
-he stay alive for a long time and is difficult to kill because of his tanky ness
-he is the most ridiculously dominant player late game if fed and this grants him all exp he wants.

Cons:
-hard to hit Q against some people so when ganking he has a chance of failing.
-cooldowns can be a problem if ganked b/c olaf needs W to have enough lifesteal along with his passive to never die. If ganked when his cooldowns are up he can die very easily.
-It is very easy to become over agressive because you are too overpowered.