Process for facilitating filtration of used lubricating oil

In a process for removing impurities from used lubricating oil wherein the oil is admixed with a treating agent to form a precipitate of the impurities and the impurities are filtered from the oil, the improvement comprising adding a polyethoxyalkylamine to said oil in an amount sufficient to coagulate at least a portion of said impurities and to improve the rate of filtration of said impurities from said oil, said polyethoxyalkylamine being predominantly present in the form of a compound represented by the general formula:

• ##STR4## wherein:
• R is an alkyl group;
• x is from 1 to about 15;
• and
• y is from 1 to about 15,
• when added to said oil if said oil has a pH less than 7, and being predominantly present in the form of a nonionic amine represented by the general formula:
• ##STR5## wherein:
• R is an alkyl group;
• x is from 1 to about 15;
• and
• y is from 1 to about 15,
• when added to said oil if said oil has a pH greater than 10.

A process for removing impurities from a collection of used lubricating oil including used diesel oil, comprising:

• adding a polyalkoxyalkylamine to said collection of used lubricating oil to coagulate soot particles and other ash-forming contaminants present therein;
• contacting said collection of used lubricating oil with a treating agent under conditions of temperature and pressure sufficient to cause said soot particles and other ash-forming contaminants present in said collection of used lubricating oil to precipitate;
• and
• filtering said collection of used lubricating oil to remove said soot particles and other ash-forming contaminants therefrom.