Ford Repair: Mustang oil, coolant system, 2 quarts

Question
I have a 2002 Ford Mustang 140,000 miles. I also drive it about 120 miles a day. Last oil change was about 2 months ago, so i am probably over due considering how much I dirve, and the age of the car. While driving my car for less than 2 miles the other day, the oil gage started flucuating wildly. Dropping and going back to the middle. Mostly dropped while I accelerated, but once gears shifted, etc, it went right back to the middle.I managed to get it back home. I pulled the dip stick out, had oil on it, wiped it off, reinserted it, and no oil came off on it...several times. I have added 4 1/2 quarts, but the dip stick still shows no oil on it, and there doesn't seem to be any oil leaks under the car. Any suggestions

Answer
The only possibility if the oil did not leak out, is that it was put in the wrong place, and never got to the dipstick. That is plenty enough oil to show up. One other alternative would be that it is going into the coolant system through a bad intake or head gasket.