Parts Washer Solvent

Thats a good question..not sure if mine is water based or not..... I got my stuff from advanced auto before it went to 50 bucks for 5 gallons...the biggest thing I do is keep it clean, make sure you get all the oily crap out first... I know it sounds stupid, like whats the point, trust me...that nice solvent will look like crap in no time flat....