How do i fix oil pan leak in a 98 cadillac deville

I would look for other leaks. If you are sure it's leaking at the dipstick tube, there is normally an o-ring where the tube presses into the engine. In general, this is an odd place for a leak, as ther eshould be no oil pressure in the pan (where the tube terminates) and unless the engine is overfilled with oil, the tube end shouldn't be immersed in oil to leak. IF there is pressure in the oil pan, that generally indicates bad rings. I have seen engines where the oil dipstick actually pops out of the tube under pressure when the engine is running due to pressure in the oil pan from blow-by at the rings.

Hello: There isn't any temporary repair. It is a major task to seal the oil leak, the engine has a two piece oil pan. To remove the oil pan either the transmission or engine has to be removed to accomplish the task.

if its just the oil pan than just the oil pan drain the oil and pull the pan, you will need some RTV gasket maker to reseal next to the crank, replace the oil pan gaskedt RVT the corners near the crank and bolt it back into place.

Between $90 and $200, depending on the condition and the engine model. See this
http://www.automotix.net/usedautoparts/1998-cadillac-deville-oil_pan-inventory.html

bad rear main seale or oil pan gasket

Keep checking the oil every time you gas up and you will be able to estimate how much oil it uses/100 miles or so. Then you can plan your trip. If the oil gets too low a warning will show up. That engine has about 7 quarts in the pan. As long as you don't run the engine low on oil the leak is just waste.

3500.00 cadillac dealer ...motor has to come out

Are you talking about the oil pan gasket, valve train cover gasket? Id so on either one you must remove the old gasket an replace it. You can try tightening the bolts some to see if that stops the leak, but if not, the gasket should be replaced.

Northstar engine, that's about right. They do take about 8 quarts.
The most common place they leak at is at the oil filter housing that attaches to the block of the engine.

after a period of driveing you have to get oil pan re tighting some times improper installion can keep it leaking also.