Why do I have to keep adding anti freeze to my vehicle, I see no leaks, there is also no signs of water in my motor oil and my vehicle is a 1999 land rover discovery 11 ,

Could be time for a new van.
The oil light is warning the driver engine oil pressure has dropped below 10 psi, not necessarily that the engine is low on oil.
Common causes for low oil pressure is a faulty oil pump or screen, or worn engine parts.
The fact you are also adding coolant and you don't see any external leaks sounds like the engine is reaching the end of its life.

look for water out tail pipe after you warm it up then rev motor to 1500-
2000, ,check oil for milky color on dip stick, and trany fluid &cooler for milky color, check coolant tank for,
smell of exhaust or just not a clean coolant smell , if in dought open a bottle of anti freez thats what it should be like, im thinking head gasket
or a small leak under pressure when driving ,gurgling is coolant moving back to coolant tank an back to motor. good luck ,
hope some of this helped , H.WOODY.

The water is leaving somewhere, either leaking out, going into the oil, or going into the exhaust. I would add a bottle of Bar's Stop Leak first. Usually if you smell the antifreeze it indicates a pretty good sized leak. I have had very good results with Bar's.
Check the carpet in the front by the firewall, between the drivers and passengers side. When the heater core leaks you usually get a wet carpet. This would be a fairly inexpensive repair relative to you other options.

Yes it is a problem, you can have a waterpump that leaks as the engine runs, when the vehicle warms up coolant expands and goes to the resovoir,as you turn the engine off and the engine cools off the fluid in the resovoir reutns to the engine but here the problem the radiator cap cant do its job when the water pump leaks

It sounds like you might have a crack in the plastic tank of the radiator. If the line was leaking, I would think you'd see some oil leaking. Any anti-freeze leaking? When the truck is cooled down, I'd check the anti-freeze and oil level.

The loss of antifreeze with no apparent leaks could be the sign of many things including blown head gasket, cracked tank, or leaking water pump. I would lean toward a head gasket first. Have you checked the oil for signs of antifreeze? A head gasket won't leak until the system is under pressure and running at normal temperature. You could also have a cracked head although that is pretty rare. Check the oil and plugs for signs of anti freeze. Also check the tanks on the side of the radiator they could be cracked which only leak while under pressure. Check all hose connections and if so equipped tranny cooler lines to make sure they are all attached correctly.

better check your engine oil ASAP.
If the oil on the dipstick is bubbley and discolored the anti-freeze is leaking into the motor.

hi, if your 100% sure that their is no coolant leaking onto the floor then look inside the car where the drivers and passenger feet are if the floor is wet then this means the heater rad is leaking and needs replacing if its dry then this could be a more serious problem now what you need to do is check your oil pull the oil stick out and check for signs of water if water is present then it will look a grey color and this would mean head gasket failure if how ever the oil level is ok and the color is normal then this could indicate that the head gasket has gone and the coolant is being burned out with the engine gasses, you need to get a compression test done and possibly a sniff test to test the coolant for signs of gasses from the engine.

Let me know how you get on or if you need further assistance ok

Oh dear !

This is a tell tale sign of....leaking head gasket / warped head.

You'll need to get the compression done on the cylinders and/or have the cooling system pressure tested.

Cheers,

if its leaking clear water on to the ground toward the back of your engine its probably just condensation from your air conditioner, if its coolant like water mixed with antifreeze then it could be a number of thingssuch as freeze plug, water pump, heater hose going into the fire wall, keep up with your radiator fluid level and if you have to keep adding coolant then you know you have a bigger problem than just condensation. condensation from your vehicle is normal