Help with fuel transfer

[IveGotNoIdea (OP)]

I have built 5 1M ton sorium extractors (I added orbital habitat to build it using industry) and one 0,75M ton tanker (again, orbital habitat and lots of fuel tanks).  My plan was to park the tanker next to extractors and move it every now or then with tugs (extractors also need tugs to move), the problem is I don't know how to efficiently transfer fuel from extractors to tanker. 
I did use "equalize fuel percentage" order, but while it does work it will require me to do this quite often when fuel reaches 80-90%. 
Next thing I tried was to remove "tanker" designation from my tanker and refuel it from harvesters, while this do work much better AFAIK I will still have to turn on tanker designation to drop fuel to the colony and then repeat whole process to get fuel from harvesters.
I'm looking for some simple way to get fuel from harvesters to my tanker without all that micromanagement.

[Erik L]

Most people put tanks in their harvesters, then send the harvesters to the nearest colony when full.

[IveGotNoIdea (OP)]

My harvesters do have tanks. . .  but moving them to and from colony will waste too much time, about 2 months for one way trip.

[clement]

There are, to my knowledge, 2 ways to handle extractors.

1.  Put engines on the extractors and when they are full, have them return to a colony or fuel storage location and unload their fuel.  Repeat till the planet is out of Sorium.

2.  Do not put any engines on the extractors.  Tug them into location.  Build a tanker/oiler type ship that is marked as a tanker.  Give it a queue of orders that will tell it to go to the extractors, fill up on fuel, and then go to the colony or fuel storage location and unload the fuel.  Mark the queue of orders to repeat, and you are all set.  The only time it needs to be modified is when the extractors need to be moved to another Sorium source.

To me, #2 is more efficient, because the Extractors can be built very large, like you have done, and you do not need to add engines to it which will be rarely used.  Also the tanker/oiler will be useful for a number of other purposes.  I build mine in the 9K to 12K ton range so that they can move fuel to where it is needed, service my military fleets, and help rescue the occasional ship that runs out of fuel.

[Marthnn]

The way I do it is using Harvester bases designed without engines, but with a good amount of fuel tanks. The design is set as tanker, and my real Tanker (set as tanker as well) can then receive the order to refuel from the Harvester. When the Harvester tanks are over 90% full, there's a message in the events screen interrupting auto turns (if I remember correctly) and I can empty it with my Tanker previously staying put at the same location (in a different task group). Plus, to empty my Harvesters of all fuel, I usually need several Tanker trips. When the Tanker fails to refuel fully, there's another message and interrupt, so I can delete all current orders. I just wish this simple mechanic could be automated.

As for Tankers, I use a single engine, plus enough fuel tanks to get about 25-35% of total size in engine.

[xeryon]

You really don't need a special command to do this.  Just size your tanker(s) and give it an order queue so that it collects what is available and returns to deliver the fuel.  It is more inefficient because your tanker will be running less than full sometimes but with the repeat toggle engaged it reduces some micromanagement.