Stock 914/6 is 7 litres ,have trawled for answers and have had 8.5,9,10 quarts and some running even more but think that's for 911's,I think the 911 tank is larger judging by the 2 I have.
I currently run 7.5 litres because I have larger oil lines and so called larger ''upgrade'' filter,just feel it should be a little more.
I can't trust the oil level on the dipstick because it is a PMS one and my tank is stock 914/6,I kinda feel this filler neck/dipstick is for their aftermarket tank .
A US quart is more than 1 litre so I'am thinking of running 9 liters total ,don't want to overfill it for obvious reasons but would like to be over to read the dipstick engine running on level ground.
TIA

I have stock -6 and it takes 9.5 quarts for mine when I change mine....no remote cooler.

With this much oil volume in the system, it will expand when hot, so be sure to be checking with the engine running and hot. There's no way that we would be starving the system with 8 or more quarts in it, and if you're on the track you don't want to be sloshing it into the vent, so I lean toward having just about 1/2-1 inch on the dipstick, no need for more in my opinion.

1 us liquid quart = 0.946 liter
Oil is measured hot with engine running.

Thanks John,always check it warmed and running,got you on the oil getting down the vent, reason for being a little cautious.
Will add more and report back .

What I do with my 930 when changing oil is to drain all the oil from the crankcase and tank into one bucket. As I add quarts of oil, I fill the empty quart containers with the used oil. I add as many quarts of oil as the old oil fills the empty containers. This gets me close enough to run the engine and top off.

:agree

I do the same thing:

Settled on 8.5 litres and have 1'' showing on dipstick,great I now have a reference point,engine is basically leak free now also.
The top mark on the stick isn't going work ,confirms my theory the PMS filler is made for their tank not a stock one,I will make some new marks.
Thanks for the helpful replies .

So that means my 16 quarts are just over 15 Liter ...

I dont know why OP said a quart is more than a liter?

I just never realized i had 15 liters of oil in my car. I really had no idea how much a quart was.