1990CrxSi

Hi.My car sucks oil like whoa.I just basically narrowed it down to these 3 things....rings,valve seals,pcv valve.my dad said it would burn oil on start up if the valve seals were bad and it doesnt do that so thats out of the question.as for the rings i dont see alot of blue smoke passed out the exhaust....the exhaust only smells kinda funny and i get an occassional puff of blue.....i was thinking it was maybe the pcv valve due to the fact that 1.the oil is being passed into the intake through the pcv valve and it is mixed with fuel and burnt 2.my plugs have a dark black coating on them 3.i cant see a whole lot of blue smoke being passed out....just smelly exhaust....anyhow tell me what you think about this....im doing a compression check on saturday to find out what might be going on but i just wanna get opinions first just to spark a bit of argument and to get facts on this deal....I want to get this car fixed up as best as i can so i can keep it up and sell it in teh summer to buy the teg i want... and oh yeah.....if it is the pcv valve,should i clean out the intake with cleaner? and should i run injector and fuel system cleaner after i put in the new fuel filter? and last but not least.....what kind of gas should i run? sunoco,mobil? and what octane?~thanks again-you guys rock.~Ryan