Loosing coolant, I notice the resevour level keeps dropping. Not loosing anypower and there is no coolant if my oil. Where else could it go. Car does not leak when pressurized ( me letting car run in driveway). Anyone else have this issue 2003 coupe??

are you smelling any coolant?see any white coolant residue in your engine bay?

are you comparing the coolant level when it is at the same temperature level? for example, if you check the coolant level first thing in the morning one day, is it the same level if you check it first thing in the morning the next day? if not, then yeah, there's a problem somewhere - air bubble, headgasket issue, etc.

before you get too worried, just make sure you're always comparing the coolant when it is the same temp.

^yes.
The level of coolant in the reservoir changes as the car temp changes.

Yea checking same temp. No burning smell. I know what your talking about, after long drives my coolant level resevoir will rise. But I have set a baseline, and its way below that.

Yes white residue on the resevoir hose, What does that mean???????????/

Radiator cap or radiator leaking?

Hmm. On the hose I the reservoir?
Possibly your reservoir over flows and that could it explain water on the house.
Also if the radiator cap is loose, the coolant can flow out of there onto the reservoir hose.
You should get your radiator cap and coolant system pressure tested.

Its weird though because its more of a powder residue that just wipes off. Its not wet or anything. And the entire hose develops this residue. I think this residue is more isolated tho this hose, perhaps some type of thermo effect more versus a splash.

the reason it is dry is because it gets on the hose then it dries up.
it's dry coolant.

pressure test the cap and system.
or start the car cold and let it warm up and just stare at the hose to see how the colant gets on it.

Do you recommend just buying the nismo cap? Most likely its the cap right?

yes. it sounds like the cap.
because the cap leaks and the coolant he's on the hose which is right below the cap.
hmmm a cap is a cap to me. haha.
the nismo cap is just to say "hey I got a nismo radiator cap."
but if you wanna spend the extra money and it looks nice. go for it.
I think they're like 15$ at an auto parts store...?

One problem just thought off, If the cap was bad, wouldn't my car be overheating?
which is not happening

not necessarily over heating because you lose a little coolant while driving then you fill it back up before you lose to much for the car to over heat.
now if you drove te car from easy coast USA to west coast, you might lose enough coant for it to over heat.

Well I don't mean the fact about loosing coolant but i mean if the cap is broken and does not hold pressure then the coolant wont circulate/flow through the system.