Ultra-low sulfur clutch-only transmission fluids
The present disclosure provides a fluid for lubricating the clutch-only portion of a wet clutch in a dual clutch transmission. The fluid provides high dynamic friction durability and comprises an oil of lubricating viscosity formulated with additive components comprising: i) at least one metal detergent; ii) at least one phosphorus-based wear preventative; iii) a phosphorylated and boronated dispersant different than the at least one phosphorus-based wear preventative; iv) a sulfurized extreme pressure agent; and a ratio between the content (ppm) of the sulfur based on the total weight of the fluid composition and a content (ppm) of phosphorus based on the total weight of the fluid composition ranging from about 2.0 to about 0.5 (ppm/ppm).
1. A clutch-only transmission fluid comprising:
a) an oil of lubricating viscosity formulated with additive components comprising:
i) up to about 1 wt % of at least one overbased metal sulfonate detergent;
ii) from about 0.01 to about 5 wt % of at least one dioleylphosphite wear preventative;
iii) from about 1 to about 6 wt % of a phosphorylated and boronated succinimide dispersant;
iv) from about 0.01 to about 10 wt % of a thiadiazole extreme pressure agent;
b) a ratio between the content (ppm) of the sulfur based on the total weight of the fluid composition and a content (ppm) of phosphorus based on the total weight of the fluid composition ranging from about 2.0 to about 0.5 (ppm/ppm); and
c) a ratio between the content (ppm) of the sulfur based on the total weight of the fluid composition and a content (ppm) of calcium based on the total weight of the fluid composition ranging from about 10.0 to about 0.5 (ppm/ppm).
2. The composition according to claim 1 , wherein said metal detergent is selected from the group consisting of calcium phenates, calcium salicylates, calcium sulfonates, and mixtures thereof.
3. The composition according to claim 1 , wherein said at least one metal detergent is an overbased calcium sulfonate.
4. The composition according to claim 3 , wherein said overbased calcium sulfonate has a total base number of between about 150 to about 450.
5. The composition according to claim 1 , wherein said composition contains from about 50 to about 100 ppm phosphorus from the dioleylphosphite compound.
6. The composition according to claim 1 , wherein said composition contains from about 50 to about 250 ppm boron from the phosphorylated and boronated dispersant.
7. The composition according to claim 1 , wherein said composition has a μ20/μ250 (aged) of between about 0.95 and 1.05.
8. A method for improving the friction performance of a clutch-only transmission, which comprises: (1) adding to the clutch-only portion of the transmission the fluid composition of claim 1 ; and (2) operating the transmission.
9. A clutch-only additive package comprising:
a) up to about 1 wt % of at least one overbased metal sulfonate detergent;
b) from about 0.01 to about 5 wt % of at least one dioleyphosphite wear preventative;
c) from about 1 to about 6 wt % of a phosphorylated and boronated succinimide dispersant;
d) from about 0.01 to about 10 wt % of a thiadiazole extreme pressure agent; and
e) a ratio between the content (ppm) of the sulfur based on the total weight of the additive package and a content (ppm) of phosphorus based on the total weight of the additive package ranging from about 2.0 to about 0.5 (ppm/ppm); and
f) a ratio between the content (ppm) of the sulfur based on the total weight of the fluid composition and a content (ppm) of calcium based on the total weight of the fluid composition ranging from about 10.0 to about 0.5 (ppm/ppm).
10. A method of improving the friction durability for a dual clutch power transmission apparatus by using an effective amount of a clutch-only transmission fluid in a clutch-only fluid reservoir in communication with said dual clutch power transmission, the transmission fluid comprising a mixture of:
(1) a major amount of a lubricating oil; and
(2) a friction durability improving effective amount of an additive combination comprising:
(a) up to about 1 wt % of at least one overbased metal sulfonate detergent;
(b) from about 0.01 to about 5 wt % of at least one dioleylphosphite wear preventative;
(c) from about 1 to about 6 wt % of a phosphorylated and boronated succinimide dispersant;
(d) from about 0.01 to about 10 wt % of a thiadiazole extreme pressure agent; and
(e) wherein a ratio between the content (ppm) of the sulfur based on the total weight of the fluid composition and a content (ppm) of phosphorus based on the total weight of the fluid composition ranges from about 2.0 to about 0.5 (ppm/ppm); and
(f) a ratio between the content (ppm) of the sulfur based on the total weight of the fluid composition and a content (ppm) of calcium based on the total weight of the fluid composition ranging from about 10.0 to about 0.5 (ppm/ppm).
11. The method of claim 10 , wherein said clutch-only transmission fluid has a μ20/μ250 (aged) of between about 0.95 and 1.05.