You do need to flush it as soon as possible. It is my understanding the two different types are not compatible. I'm surprised no one has chimed in to say which kind should be in your engine. I'm just not sure myself.


With the heater core leaking, if it is a bad leak, the carpet on the passenger side should get wet when you are using the heater. Have you noticed that at any time?

From everything you have stated here it sounds like it is just the heater core.
Maybe you'll be lucky and everything else will be OK.

 

Just becareful. I know a guy that works at a Ford dealership and he's told me some horror stories on these engines hydrolocking after changing the coolant.

 

I don't think that is a concern because of flushing the radiator. Flushing it and the engine does not build the pressure there is in the system while the engine is running. When the engine is hot it runs about 16 pounds of pressure. During a flush there is no pressure

 

no the floor is absolutely never wet. idk if i mentioned this before, but i refill the reserve like once a week..

and also, i took a picture of the stuff i keep finding in the radiator...turns out its BROWN when wiped on a white paper towel. the color is the same color of the stop leak i first used...but that was quite awhile back.
heres a link to the pic:
http://tinypic.com/r/2s98tpu/6


and one last thing- whenever i buy coolant, i always get the stuff that says "compatible with all light duty trucks"

 

I was looking at the picture of the radiator cap. It's hard to tell in the pic because of all the crud on it. But it looks like it may not be sealing good.
It has to have a good seal so it will hold the pressure of your cooling system. If it's not sealing, you could be losing coolant through it while your driving, and that would explain also why you smell it when you stop. But if you're not having to add coolant in the summertime that wouldn't be the problem.
But you have to flush that system without a doubt.

 

i dont know about filling it in the summer...it didnt waste alot because i used the stop leak. so what do i do to fix this if its not sealing tight?

 

the best thing would be to flush the system out both the radiator and heater core, and get a new radiator cap.

also concerning the stop leak i would stop using that b/c after a while of having the stop leak in it will clog up your heater core and u wont have heat. i had stop leak in my truck for 2 months and then my heat stopped working so good.

also that year f150s can either have the yellow or green color anti frease in it, NEVER use the orange or red color. and never mix the types

 

yeah my heat stopped working a lil while back. it sucked but its fine now