Ive just noticed recently the heat blowing cold when the engine is idling. When im driving, it blows hot and its all normal, but as soon as I come to a light, the heat starts blowing cold. Its a 98 Disco, TIA

 

You need to bleed your cooling system. You may have a full coolant bottle, but there is air trapped somewhere.

 

so I need a coolant flush? any DIY links? I was worried it was maybe head gasket or is this a common problem with the heat?

 

You are low on coolant.
At idle there is not enough coolant to go around, at higher RPM the water pump pushes it around fast enough to keep you warm.
If you were in park and revved the engine it would blow warm again.

 

Since the coolant reservoir is NOT clear, how do I check to see the coolant level

 

ok, i just opened the cap and checked and yes it is practically empty, just some green coolant, which coolant to use? Must is be OEM LAND ROVER or can I just pick something up from AUTOZONE, WALMART.... etc? Also, should I top it off with fluid?

 

Open the cap with the engine cool. Do not open hot.

The process for the bleed is on here somewhere. Do a search for it. You are losing coolant somewhere. Might be a head gasket. You need to find it and do not let it get hot

 

Regular green coolant youcan get it mixed50/50 already. There is a stick thingy coming up from the bottom when you look inside. Fill it to the top of that.

 

I know where its loosing the coolant, its an EXTERNAL head gasket leak but very small. Its literally a drip or two every once in a while. So it shouldn't worry about bleeding but instead just putting coolant in it? Also, what coolant should I use?

 

So that pass that stick in inside the reservoir? That looks like a divider? This coolant will do?