Dealer might have overfilled my oil
 

I had my oil changed at 3500 miles on my 05 to synthetic, and it runs smooth though a tad sluggish at time. Here's the deal, i brought them 6 quarts knowing that the s2000 takes 5.1 (so the manual says). They never gave me back any extra. I'm a tad worried that they may have overfilled by 0.9 quarts, but when i check the oil it only shows the oil over by a tad bit. Would the dipstick show a significant overfill if there was one? Or will it only go up to the hash mark area and not show further. Should i be concerned with this? It just struck me know that they could have overfilled this, but i've driven the car for a about 500 miles already, no problems and it feels great after its been warmed up a bit.

No, you should not worry about oil overfill because your dipstick shows only little over full mark. The dealer mechanic keeps the un-used portion of the 6th quart for himself. Next time just give them 5 quarts, then add a little when you check the oil level at the time you pickup your car. That way you will be sure that your oil level is good and do not waste almost 1 quart of synthetic oil (almost $5)

So if some moron overfilled the hell out of it, the dipstick would show it, or else the engine just wouldn't have taken it. But my concern ( a full 1 quart overfill) is just no really possible. Correct?

You can overfill by a little. It isn't a problem until the crank shaft is sitting in the oil and causes foaming. You would probably notice that on the dip stick and/or inside the oil fill cap. I would say you are good to go. TR-S2K is correct. If you overfilled, the dip stick would show it. Next time give them 5 Qts. and bring it to the top yourself. You can safely run at the bottom of the XXXX's on the dip stick.

One quart overfill, while quite possible, did not happen to you or you would see it on the dip stick and probably see some foam in the oil. If foaming was there, you would not miss it.

You do know that Honda doesn't advise switching to synthetic until 7,500 miles right?

my S fills up at 5.4

Next time,do it yourself !!!

I felt with the amount of time i was storing the engine and the distance of the startups that i was doing that i was going to switch to Synthetic at 3500 (first oil change). I know honda recommends break in oil for 7500 miles+, etc. But for example, toyota did the same thing with the GTS engine yet Lotus puts a synthetic blend in to start and switches to full synthetic at 1000. I made a judgement call on the change, and i was pretty happy with the intial result. The car felt smooth and didn't burn off oil. I burned off nearly a full 2 quarts in the first 3500 miles, and i was adding average dino oil. Given its only 5.1 quarts, the moly content was severely diluted at that point so i saw no reason to wait because of the manual.

You burned 2 quarts in the first 3500 miles? I have the same year and burned absolutely zero x's. That seems excessive.

If you are paranoid and they indeed put 6 full quarts in it, just make sure you let the car warm up before pushing it too hard. The only real danger of a slight overfill is when the oil is still cold and puts excess pressure on the head gasket, etc.

Once it is warmed up, it is probably more beneficial to your car than detrimental, especially if you corner hard in the car or subdue it to steep inclines/declines.