As onzedge says, it's normal for it to rise/fall a bit as the engine heats/cools.

Since you haven't reported any drips on the driveway, I'd say that it's just some spillage from the hose change. It's all but impossible to avoid spilling some a/f when you pull a hose.

Just keep a close eye on it for a few weeks, in case it is a leak of some sort. Might help with the smell to rinse the area and the tray with plenty of water.

The other thing to do after a fresh fill is in the morning pop the cap on the coolant neck off and make sure the level in the motor hasn't dropped and an air bubble formed in the neck.

I also, for good measure, appease the gods by sacrificing a chicken (ore is it a goat?) prior to checking my fluid levels to help assure a correct reading.

I always preferred a human sacrifice on the Z, the coolant systems on our cars need that like extra divine help to work properly.

Take a look at the CO (Engine Cooling System) section of the FSM for more info on what is supposed to be going on. Link in my sig.

as others mentioned, it's most likely spilt coolant during the replacement process. they shouldve hosed down the engine bay afterwards to remove all thd spilt, sticky smelly mess - because it's coolant it wont evaporate like plain water so it just has to be washed off.

could be a chance some coolant is leaking in your heatercore? can you put the cabin air intake to recirc and see if the smell subsides?

It is probably nothing but I'm jus letting you know what it could be.

Thanks guys for the posts. I drove it pretty hard tonight and when I pulled it into the garage there was no smell. Very weird cause thats the 1st time in 3 weeks it hasent smelled. The resovoir tank was at the same level as before so it didnt drop or rise at all. I will take off the under tray and clean it just to make sure and il clean the engine as I always do each month anyway. Im a freak about the engine bay being clean. I will keep this post updated.

When they put the new coolant in was it supposed to be 100% fluid or was there supposed to be water mixed in also?

Can't tell from here. Many antifreezes, including the stuff from Nissan, come pre-mixed nowadays.

If you are seeing two liquids that aren't mixing, one of the fluids may be oil. If so, you need to track down the source.

Some come premixed and some are full strength and require a 50% dilution with DISTILLED water. Check the bottle.

I use the Nissan "long life" blue stuff which comes pre-diluted.

Il have to ask the dealer what they used. I dont see 2 liquids I just noticed its very bright green and seems to smell stronger than the stuff that was in the car when I 1st baught it.

You can get an antifreeze hydrometer at most auto parts stores. WalMart has one for $2.54.

Thank u I will definitely pick one up. I drove the z on a road trip this weekend and noticed each time the temp git above 200degrees I could smell the coolant strong. Under 200 degrees no smell?? Thats strange and its making me crazy cause it was perfect until I had nissan drain the old fluid and put new stuff in.

Only smelling it when the engine is warm is normal. Assuming it's just a spill, it should clean up with some water. Pull the tray and rinse it off then take a hose to the engine compartment.