Hello there

I have a 1999 Silverado 1500 with the 5.3l engine. Recently, it has been using both oil and coolant. Every couple days the check coolant light comes on and I have to put more anti freeze in it. It also requires oil to be added between oil changes. I've done a lot of searching on the internet and have discovered it to possibly be bad head gaskets or possibly intake manifold gasket. I have not seen any leaks under the truck either

Any further insight is very appreciated

 

I would suspect head gasket. With coolant loss, any white smoke & sweet smell to exhaust? Any evidence coolant on oil dipstick?