Just checking my coolant and I noticed the inside of the res is super dirty. The coolant is beautiful in the radiator and the res but idk what it is? Would like a quick answer, Thanks! Also I've tried washing it out with water but it's stuck.
ive got that too but my parts car reservoir doesnt, i think i saw more of it show up after my engine overheated a bunch, i think its gunk from the cooling passages after heating but i could be wrong.
buy a new one they are around $15, had a bunch of crap in my 99 si after headgasket issues, i just bought a new one rather than try to clean it. rock auto is where i got mine