i first thought it was all rust.
but as i ran water through it. it was oily. the coolant reservour was filled with brown and thick fluid. at first i just thought it was rust because its been a long time since i changed the coolant and oil. i flushed everything and cleaned it. and now new coolant and engine oil is inside. but for some reason it mixes. the coolant reservour turns all brown again.
what do i have to do to fix it

Let's hope its not something like a cracked head or blown head gasket.

Here's what I think you might be seeing?????. If you use the green colored antifreeze it seems to have a chemical reaction to the aluminum engine components. And within a short time the green color is gone and replaced with brownish color. Go to your Toyota dealer and buy Toyota antifreeze. Its red in color. You can purchased 50-50 premix or concentrated where you need to add demineralized water. Drain your engine of all coolant and replace with Toyota brand.

Do a search in the Camry forum under engine coolant or antifreeze there's some great advice to found there.

Post back and let us know what you found out.