Very strange. Definately let us know what you find. Hopefully you figure this one out. The problem you're having would drive me crazy until I figured it out - I'm sure you feel the same way.

 

Im sure theres some kind of low oil light. But ive got an UPDATE!

So yesterday before i left work at 5:30, i checked the oil level. Which was exactly where i left it since i topped it up yesterday morning. I drove back home pulled it in the garage (normally i park on the driveway) and let it sit for a while, looking at things under the car.

Finally checked the oil after it sat for a while (about 1 hour) then i called it a night. This morning i went to pull it out of the garage and noticed now a very large oil spot on the floor which was still a bit wet.

It would make sence that i could not see it on my driveway because my driveway is already covered in spots from my leaky tranny line (which i did fix). So im wondering why it seems to only leak during the night time when its nice and cold out and i may have a thought on this one.

Could it be that i may have some kind of seal or gasket that while the motor is warm and everything has expanded stays tightly sealed, but once it has the time during the night (oddly cold weather in NY already) the seal contracts and there by allows the oil seep through?

Also the dipstick tube seems fine.

 

it kind of makes sense that when the engine is hot that the gaskets do expand a tad because of the heat, and when it cools down they do shrink, a tiny bit, put a piece of cardboard or oil soaking rags under the car, so you can lift the car right up and find exactly the area the leak is coming from.

 

You previously mentioned replacing an overtight oil filter. Did the gasket from that filter remain in the block so the gaskets are doubled up? I have seen this happen in the past (but not on a Monte) and the car would leak oil when sitting for a period of time. Was the puddle of oil directly below the area where the filter is located? If there is a trail of oil on the side of the filter it is a possibility.

 

It could be possible that the oil pan gasket is leaking I think. After the car cools all the oil will collect in the pan.

 

I don't know if it's a common issue on the 7th Gen but I wouldn't overlook the rear head gasket