Riddle me this...

[Fordboy300]

Hey guys,  so recently I'll fill my coolant reservoir not always the way but a little less then half way and I'll drive my truck around for the weekend maybe a little bit more.
 Today I checked under the hood and noticed the reservoir is almost empty there is some in there it has no leaks whatsoever and the radiator is always full.  

I'm almost positive that it doesnt burn it so we could check that on off the list.  

[delco1946]

Have any stains around your rad cap? My truck did that constantly until I replaced the old rad cap which had worn out. Its a 13 dollar part so a cheap place to start that could easily fix the problem.

As the engine heats up, coolant would push out the around the cap instead of going back through the hose into the reservoir. AKA not function as intended. Then as it cooled, it would replace the lost fluid with that stored in the reservoir, as intended. Eventually, the reservoir goes bone dry.

[Gsmblue]

Have you checked your oil? My intake manifold gasket blew so coolant was getting in the exhaust and the oil.

[ArdWrknTrk]

My truck always goes almost empty.
I don't know why. I've pressure tested the system and the head gaskets are good, I have no leaks anywhere I can find.

But when my truck is hot, it's full to the brim.
I think my Bricknose reservoir is just not enough for the volume of my radiator and cooling/heating system.

[Fordboy300]

Yes I just changed the oil last week smells a little like fuel but I know the cause.