I'm looking at this car on Craigslist for 2500$ with 178xxx mils on the odometer. He said the car needs to be rev'd up in order to idle on its own , and when its not warmed up the car blows white smoke out the exhaust very noticable. He says it happens when he stops or downshift to first gear.

Idk whats the problem nd why it blows white smoke and I wanna know how it can be fixed.

 

you can fix it with a newly rebuilt engine.
The Engine is shot due to a coolant seal.

 

Damm apex seals . How can you keep them live longer? Best ways to maintain your rotary also?

 

apex seals are metal and on the rotors internally.
Coolant seals are in between the irons and housings.Think of them as a rubber O ring that seals the Slices of an engine sandwich together.
One of those O rings lets go and the coolant gets inside the combustion area and the engine starts burning coolant..white smoke..like a blown head gasket.
depending on where it has let go it can either Blow into the cooling system or suck coolant into the engine.

Reliability is proper maintenance.Period.Maintenance is oil,filters,plugs,hoses and then paying attention to 25 year old stuff that tends to break down and needs fixing.