Thermally stabilized polyorganosiloxane oil

A fusing system for an electrostatographic printing machine comprising a heated fuser member and a pressure member forming a fusing nip there between, a supply of release agent and means to deliver a release agent to the surface of the fuser member, said release agent comprising a polyorganosiloxane oil and as the thermal stabilizer the reaction product of chloroplatinic acid and a member selected from the group consisting of a cyclic polyorganosiloxane having the formula:

• ##STR12## where R.sub.3 is an alkyl radical having 1 to 6 carbon atoms and R.sub.4 is selected from the group consisting of alkene and alkyne radicals having 2 to 8 carbon atoms and n is from 3 to 6;
• a linear polyorganosiloxane having the formula:
• ##STR13## where R.sub.1 and R.sub.2 are selected from the group consisting of hydroxy and alkyl, alkoxy, alkene and alkyne radicals having 1 to 10 carbon atoms provided at least one of R.sub.1 and R.sub.2 is alkene or alkyne and m is from 0 to 50 and mixtures thereof present in an amount to provide at least 5 parts per million of platinum in said oil.