Silicon-containing compounds for lubricants
The present disclosure relates to lubricating compositions and methods of lubricating a spark-ignition engine effective to depress low-speed pre-ignition (LSPI) events and to maintain low foaming and/or aeration through selected silicon chemistries and treat rates.
1. A passenger car motor oil configured to maintain low foam and/or low aeration during lubrication, the passenger car motor oil comprising:
one or more base oils of lubricating viscosity;
about 15 ppm or less of silicon provided from a polydialkylsiloxane antifoam polymer; and
at least about 100 ppm of additional silicon provided from a silicon-containing compound selected from a siloxane derivative, wherein the silicon-containing compound providing the additional silicon has a molecular weight of no more than about 650; and
wherein the additional silicon is provided by a compound of Formula II
wherein
each R is a methyl group;
R 1 is a —R 2 —[O—R 3 ] n —OR 4 polyether group with R 2 being a C 3 hydrocarbyl group, R 3 being a C 1 to C 2 hydrocarbyl group, R 4 being either hydrogen or a methyl group;
m being an integer of 0 when R 4 is hydrogen and m being an integer of 1 when R 4 is a methyl group, and
n being an integer of 1.
2. The passenger car motor oil of claim 1 , wherein the polydialkylsiloxane antifoam polymer is a polydimethylsiloxane polymer having a number average molecular weight of about 50,000 or greater.
3. The passenger car motor oil of claim 1 , wherein the silicon-containing compound providing the additional silicon has no more than 10 silicon-to-oxygen bonds per compound.
4. The passenger car motor oil of claim 1 , wherein the passenger car motor oil entrains a lower volume of free air when operated in a naturally aspirated engine as compared to a reference motor oil without the additional silicon provided from the silicon-containing compound.
5. The passenger car motor oil of claim 4 , wherein the passenger car motor oil exhibits no more than 5 average events pursuant to a Sequence IX low speed pre-ignition test of ASTM D8291 and/or exhibits no more than 8 maximum events pursuant to the Sequence IX low speed pre-ignition test of ASTM D8291.
6. The passenger car motor oil of claim 1 , wherein the passenger car motor oil includes about 100 to about 300 ppm of the additional silicon.
7. The passenger car motor oil of claim 1 , wherein the passenger car motor oil includes about 100 to about 250 ppm of the additional silicon.
8. A method of lubricating a combustion engine with a passenger car motor oil to provide low foaming and/or low aeration with increased levels of silicon, the method comprising:
lubricating the combustion engine with the passenger car motor oil, wherein the passenger car motor oil includes (i) one or more base oils of lubricating viscosity; (ii) about 15 ppm or less of silicon provided from a polydialkylsiloxane antifoam polymer; and (iii) at least about 100 ppm of additional silicon provided from a silicon-containing compound selected from a siloxane derivative, wherein the silicon-containing compounding providing the additional silicon has a molecular weight of no more than about 650; and wherein the additional silicon is provided by a compound of Formula II
wherein each R is a methyl group: R 1 is a —R 2 —[O—R 3 ] n —OR 4 polyether group with R 2 being a C 3 hydrocarbyl group, R 3 being a C 1 to C 2 hydrocarbyl group, R 4 being either hydrogen or a methyl group: m being an integer of 0 when R 4 is hydrogen and m being an integer of 1 when R 4 is a methyl group, and n being an integer of 1; and
wherein the passenger car motor oil entrains a lower volume of free air when operated in a naturally aspirated engine as compared to a reference motor oil without the additional silicon provided from a silicon-containing compound.
9. The method of claim 8 , wherein the passenger car motor oil exhibits no more than 5 average events pursuant to a Sequence IX low speed pre-ignition test of ASTM D8291 and/or exhibits no more than 8 maximum events pursuant to the Sequence IX low speed pre-ignition test of ASTM D8291.
10. The method of claim 8 , wherein the polydialkylsiloxane antifoam polymer is a polydimethylsiloxane polymer having a number average molecular weight of at least about 50,000.
11. The method of claim 8 , wherein the silicon-containing compound providing the additional silicon has no more than 10 silicon-to-oxygen bonds/compound.
12. The method of claim 8 , wherein the passenger car motor oil includes about 100 to about 300 ppm of the additional silicon.
13. The method of claim 8 , wherein the passenger car motor oil includes about 100 to about 250 ppm of the additional silicon.