This application is directed to lubricant and fuel additives and compositions thereof.  More particularly, this application is directed to liquid hydrocarbyl or hydrocarbyloxy fuels containing an effective multifunctional amount of an ester-type polymer containing additional sulfur ester moieties, thereby providing exceptional dispersant/detergent activity and thermal stability. 
The use of ester-containing or polymeric ester or polymeric ester/amide type carboxylic dispersants are well known, such as those described in U.S. Pat.  Nos.  3,341,547, 3,632,510, 3,632,511, 3,697,428, or 3,725,441.  These have been used in a variety of commercial lubricant and fuel applications for several decades. 
The use of sulfur-ester containing additives have been reported in the literature, primarily in polymer stabilizing applications. 
However no prior art known to applicant discloses and/or claims lubricant liquid hydrocarbyl or hydrocarby or hydrocarbyloxy fuel compositions comprising ester-type alkenyl succinic anhydride-derived ashless dispersants having additional integral sulfur-ester moieties.