dispersant

---

is an engine oil additive that helps prevent sludge, varnish, and other engine deposits by keeping particles suspended in a colloidal state (see colloid) within the bulk oil. Dispersants are normally used in conjunction with detergents. A dispersant can be distinguished from a detergent in that the former may be non-metallic and, thus, does not leave an ash when the oil is burned; hence, the term ashless dispersant.