Lubricating oil compositions for improved cleanliness in ammonia engines and methods of use thereof

A method of improving engine cleanliness in an ammonia fueled internal combustion engine (AICE) comprising:

• i) providing to the ammonia fueled internal combustion engine a lubricating oil composition comprising or resulting from the admixing of:
• a) an oil of lubricating viscosity at greater than 50 wt. % of the composition comprising a Group I base oil, a Group II base oil, a Group III base oil, a Group IV base oil, or combinations thereof;
• b) optionally, one or more, optionally borated, higher molecular weight polyisobutylene succinimide (PIBSA-PAM) dispersant (Mn 1600 g/mol or more);
• c) one or more, optionally borated, lower molecular weight polyisobutylene succinimide (PIBSA-PAM) dispersant (Mn less than 1600 g/mol), wherein the treat level of the combination of the higher molecular weight PIBSA-PAM and lower molecular weight PIBSA-PAM is from 2.5 to 12.0 wt. % of the composition, wherein the treat level of the lower molecular weight PIBSA-PAM is from 0.1 to 9.0 wt. % of the composition, and wherein the treat level of the higher molecular weight PIBSA-PAM is less than or equal to 3.0 wt. %;
• and
• d) one or more overbased detergents selected from the group consisting of a metal salicylate, a metal carboxylate, a mixture of a metal salicylate and a metal sulfonate, a mixture of a metal carboxylate and a metal sulfonate, and combinations thereof, wherein the one or more overbased detergents have a Total Base Number (mgKOH/g) greater than or equal to 9 and less than or equal to 500 and deliver at least 5 mmol of total soap to the composition;
• and
• e) one or more zinc dialkyl dithiophosphate (ZDDP) compounds at from about 0.08 wt. % to about 2.0 wt. % of the lubricating oil composition;
• wherein the lubricating oil composition having a total sulfated ash of less than or equal to 5.0 wt. %, and a total phosphorous level of less than or equal to 0.120 wt. %, and an overall viscosity of less than or equal to 25 cSt (KV100);
• and
• ii) providing a fuel comprising ammonia to the ammonia fueled internal combustion engine;
• and
• iii) combusting the fuel in the ammonia fueled internal combustion engine;
• and
• wherein the lubricating oil composition upon exposure to ammonia contamination per the NOx-Ammonia exposure protocol results in a MCT (GFC Lu 27-A-13) cleanliness merit rating change versus a comparable lubricating oil composition not exposed to ammonia contamination of less than or equal to 4.0 merits.

A concentrate comprising or resulting from the admixing of:

• from 1 to less than or equal to 50 wt. % of one or more base oils;
• from 2 to 40 wt. % of one or more overbased detergents selected from the group consisting of a metal salicylate, a metal carboxylate, a mixture of a metal salicylate and a metal sulfonate, a mixture of a metal carboxylate and a metal sulfonate and combinations thereof, wherein the one or more overbased detergents have a Total Base Number (mgKOH/g) greater than or equal to 9 and less than or equal to 500 and deliver at least 5 mmol of total soap to the composition;
• from 2 to 40 wt. % of optionally, one or more, optionally borated, higher molecular weight polyisobutylene succinimide (PIBSA-PAM) dispersant (Mn 1600 g/mol or more), and one or more, optionally borated, lower molecular weight polyisobutylene succinimide (PIBSA-PAM) dispersant (Mn less than 1600 g/mol), and
• from 2 to 20 wt. % of one or more zinc hydrocarbyl diphosphate compounds, wherein the one or more zinc hydrocarbyl diphosphate compounds include hydrocarbyl groups derived from one or more primary alcohols, one or more secondary alcohols or a combination of primary and secondary alcohols.