Shimano XT hydraulic lever leak?

[TBLS]

Jumped on my fat bike and rear lever pulled all the way to bars. Looked at lever and pulled plastic cap off of bolt that hydraulic hose connects to lever and covered with fluid.

Bolt was loose so I tightened but how tight should it be? Before I add fluid and bleed any other advice or reasons it would leak. Have bled brakes but never installed hoses, etc.

Thx in advance as want to avoid bike shop visit/riding delay

[dddd]

The bolt has substantial threading, so tighten as a normal nut.

After such fluid loss, be aware that fluid volume lost comes from the reservoir, and that air getting into the system is a likelihood at this point.

Check the braking action and be cautious for a while of any changes in lever feel that might occur on the first ride, especially after the bike is perhaps hung from a hook or put upside-down.

A simple brake fluid refill/bleed would be appropriate at this time.

[P K]

Just to add to this:

Behind that bolt is the "olive" which is a single-use brass compression sleeve that makes the seal around the hose to the lever. If you re-tighten then re-fill/bleed the system and it still leaks you'll need to replace the olive/barb. I'll guess you don't have the hose cutter, olive and barb you'd need for this, which will mean a trip to the bike shop after all.

[dddd]

One more thing is that these connections don't often loosen on their own, so be sure to check the other lever for possible similar insufficient tightening.
Heavy tightening not needed, the first time should compress the olive, and that would normally be enough to prevent the nut from loosening.
But it's a mountain bike, so a solid impact to the connection nut might have helped it to loosen(?).