US3873455A

US3873455A - Five-grade motor oil for internal combustion engines

Info

Publication number: US3873455A
Application number: US329033A
Authority: US
Inventors: Richard D Schieman
Original assignee: Individual
Current assignee: Individual
Priority date: 1971-11-26
Filing date: 1973-02-02
Publication date: 1975-03-25
Anticipated expiration: 1992-03-25
Also published as: CA984372A; DE2250467A1; GB1404660A; FR2160840B1; JPS4860702A; FR2160840A1

Abstract

A five-grade motor oil composition for gasoline internal combustion engines having improved oil consumption and lowtemperature cranking characteristics comprises a base oil blend of two solvent extracted neutral mineral oils and a dewaxed and dearomatized catalytically cracked mineral oil stock, in combination with suitable lube oil additives. The finished oil formulation meets the requirements for a SAE 5W-40 motor oil.

Description

United States Patent [191 Schieman [451 Mar. 25, 1975 1 FIVE-GRADE MOTOR OIL FOR INTERNAL COMBUSTION ENGINES [76] Inventor: Richard D. Schieman, 188

Moorewood Ave., Avon Lake, Ohio 44012 [22] Filed: Feb. 2, 1973 [21] Appl. No.: 329,033

Related US. Application Data [63] Continuation-impart of Ser. No. 202,650, Nov. 26,

1971, abandoned.

3,595,967 7/1971 Riedel et a1, 252/327 E X OTHER PUBLICATIONS Smalheer et al., Lubricant Additives, 1967, pp. 28.

Primary Examiner-Patrick P. Garvin Assistant Examiner-Andrew H. Metz Attorney, Agent, or Firm-Herbert D. Knudsen; Sherman J. Kemmer; John F. Jones [57] ABSTRACT A five-grade motor oil composition for gasoline internal combustion engines having improved oil consumption and low-temperature cranking characteristics comprises a base oil blend of two solvent extracted neutral mineral oils and a dewaxed and dearomatized catalytically cracked mineral oil stock, in combination with suitable lube oil additives. The finished oil formulation meets the requirements for a SAE 5W-40 motor oil.

10 Claims, N0 Drawings FIVE-GRADE MOTOR OIL FOR INTERNAL COMBUSTION ENGINES This application is a continuation in part of US. Pat. Ser. No. 202,650 filed Nov. 26, 1971 and now abandoned.

This invention relates to a motor oil composition for gasoline internal combustion engines. More particularly this invention relates to a blended motor oil base stock that will provide adequate lubrication for internal combustion engines despite extreme climatic conditions.

Normally, lubricating oils must provide minimal wear in an engine under operating temperatures at the cylinder walls in the combustion zone ranging from well below F. on a winter morning to well above 400F. To perform this function satisfactorily, the oil must have thermal stability, shear stability and a resistance to breaking down into harmful deposits which show up as varnish within the engine. Another important criterion for motor oil performance is that it have low consumption in an engine, particularly because environmental pollution caused by automobile emissions is of concern.

A market has been developed for multi-grade motor oils which besides having all of the characteristics desired in a superior motor oil should provide adequate lubrication throughout the year regardless of climatic conditions or severity of usage.

lt is therefor an object of this invention to provide a base oil for a motor oil formulation which comprises a unique blend of several refinery lubricating oil stocks in certain specific proportions which when used in con junction with well known multi-functional dispersantdetergent additives, viscosity index improvers, and pour point depressants will be consumed at very low levels in the operation of the engine and will meet the required specifications for a five-grade SAE 5W-40 crankcase oil.

A serious problem generally associated with 5W grade motor oils is oil consumption. It has long been recognized that while 5W oils have excellent low temperature cranking properties, they usually are limited to use at ambient temperatures not exceeding 60F. due to undesirable oil consumption characteristics. At the same time oils of W grade are usually restrictive to low temperature cranking characteristics and are not useful below 0F., however they do not have the oil consumption problems above 60F. associated with the SW oils. No known blend of refined petroleum-base has previously been described which will meet the specifications required for a multi-grade 5W4O motor oil having both satisfactory consumption properties and low-temperature cranking properties. It is therefor a further object of this invention to provide a base oil blend for a SAE 5W-40 oil which satisfies both of the above criteria.

The most preferred oils of the instant invention provide a finished 5W-40 motor oil wherein no more than 12 volume percent of the oil boils below 725F., has a minimum 300F. viscosity of 6.5 centistokes, a minimum 210F. viscosity of 14.7 centistokes, a maximum 0F. viscosity of 12 poises (cold crank simulator viscosity) and a maximum consumption rate in the engine of about 5.8 quarts/64 hours of oil as defined by the Sequence IIIC test (SAE-General Motors-6041).

In accordance with this invention, the base oil for the multi-grade motor oil comprises a specific blend of two selected solvent extracted neutral mineral oils, one having a viscosity of about 100 to about 150 SSU preferably about 140 SSU at 100F., and the other having a viscosity of about 700 to about 800 SSU preferably about 750 SSU at 100F., (hereinafter referred to as SEN 100-150 and SEN 700-800 respectively) and a second component which is dewaxed and dearomatized catalytically cracked mineral oil stock having an average viscosity of about to about SSU preferably about 85 SSU at F. (herein referred to as HVl 75-90 oil).

Solvent extracted neutral oils are well-known standard mineral oil refinery stocks. The HVl 75-90 oil is an end product obtained by fractionating the effluent from a catalytic cracking zone in a tower, running off the bottoms from the tower into a catalyst separation zone where the catalyst fines are settled out, decanting the supernatant phase called cycle oil or decanted oil, and extracting the decanted oil with a solvent for the removal of aromatics. The extract phase containing the aromatics is removed, and the raffinate phase containing the paraffinic stock is led to a dewaxing zone where wax is separated, leaving a dewaxed oil product which is the feed stock for the HVI oil used. The HVl 759O oil is obtained by fractionally distilling this feedstock. A process for obtaining a wax composition from a catalytic cracking stock, leaving a dewaxed oil product, is described in US. Pat. No. 2,660,553.

The base oil of this invention comprises a carefully balanced mixture of the aforementioned refinery stocks so that a light component and a heavy component are formulated and are combined to fulfill the SAE SW and the SAE 40 requirements of the multigrade motor oil. The light component which fulfills the SAE5W requirement of the motor oil comprises a blend of two fractions of the dewaxed, dearomatized, fractionated catalytically cracked stock, which has superior thermal stability as compared with solvent extracted neutral oilsof comparable boiling range, and a unique ability to reduce the viscosity of 0F. without decreasing the viscosity at 210F. in the same ratio. The heavy component which fulfills the SAE-40 requirement is derived from a blend of the SEN 100-150 oil and the SEN 700-800 oil. The properties of typical mineral oil stocks blended to formulate the motor oil of this invention are given in Table l.

The high boiling range of the light component of this lubricating oil formulation is uniquely obtained by combining two fractions of the dewaxed, dearomatized, catalytically cracked stock in certain definite ratios which apparently azeotrope, thereby retaining the high boiling range while reducing viscosity. It is highly important that a minimum amount of this light component boil below 725F. and that the 210F. viscosity remain as high as possible in order to minimize the quality of the oil consumed by the engine. The trend in oil consumption by the engine as related to the amount of oil in the finished oil boiling below 725F. is illustrated by the data given in Table II. These data show within limits of experimental error that oils containing substantially more than 25 volume percent of components boiling below 725F. increase consumption above the tolerable limits. Preferred are light components where no more than 15 volume percent boil below 725F.,

and most preferred are those light components where no more than 12 volume percent boil below 725F.

In order for the light component of this base oil formulation to meet the consumption restriction and to fulfill the SW requirement in the finished oil, the light component must have a minimum viscosity at 210F. of about 3.2 centistokes, a maximum viscosity at F. of about 5.9 poises, coupled with a restrictive boiling range of between about 650 to 800F. with no more than about 25 percent by volume of the oil boiling below 725F. The light component of the base oil of this invention is conveniently a blend of from about to 18 percent by volume of an oil fraction of a dewaxed, dearomatized, catalytically cracked stock having a maximum of about 80 percent of the oil by volume boiling below 725F., a 210F. viscosity in the range of from about 2.8 to 2.9 centistokes, a 100F. viscosity of from about 11.5 to 11.9 centistokes and a 0 F. viscosity of from about 2.2 to 2.9 poises, combined with from about 82 to 95 percent by volume of a dewaxed, dearomatized, catalytically cracked oil fraction having a maximum of 15 percent by volume of the oil boiling below 725F., a 210F. viscosity of from about 3.8 to 4.0 centistokes, a 100F. viscosity of from about 18.7 to 19.0 centistokes and a 0F. viscosity of from about 4.5 to 5.5 poises. Typical catalytically cracked oil fractions suitable for use in the light component of the base oil formulation are shown in Table l. The light component of the base oil could also be prepared from a single fraction.

The ratio of the two oil fractions that constitute the base oil may vary to some extent with the type of additive employed in the finished oil, since in instances where the additive contains a diluent oil, the volatility of the base oil must be adjusted in accordance with the volatility of the diluent oil employed.

The heavy component of the base oil in this invention in order to fulfill the SAE 40 requirement of the finished oil must have a 300F. viscosity of at least 2.5 centistokes in order to provide sufficient hydrodynamic film strength at high temperatures, a minimum 210F. viscosity of about 6.4 centistokes, a maximum 0F. viscosity of about 20.0 poises and with little or no volume percent of the oil boiling below 725F.

The heavy component having the above properties is obtainable by blending from about 70 to about 85 preferably 72 to 84 volume percent of a SEN 100-150 oil with from about 15 to about 30 preferably 16 to 28 volume percent of a SEN 700-800 oil, the properties of typical oils being given in Table 1.

Although the requirements for a 5W-40 base oil can be essentially met with the oil blend comprising the light component of the present formulation, there is need for the heavy component to fulfill the 300F. viscosity requirement essential for adequate film strength of the oil at high temperatures. Concomitantly, the heavy component should have properties which do not increase the 0F. viscosity of the base oil formulation to above about 5.7 poises. Such an oil is obtained with the blend of a SEN 700-800 oil with a SEN 100-150 oil.

While a blend of the SEN 100 oil and the SEN 750 oil meet the viscometric requirements for the base oil at 0F., minor problems associated with volatility occur with this particular formulation. However, the SEN 140 oil in the heavy component blend can be replaced with a SEN 100 oil provided the boiling range of the SEN 100 is restricted to within approximately 720 to 835 F. It is again apparent that the initial part of such an oil is closely restricted to the region of 725F. Viscometrically such an oil must have a viscosity of from about 3.9 to 4.2 centistokes at 210F. and a maximum viscosity of about 6.0 poises at 0F.

To attain a base oil that meets the viscosity and volatility criteria for the finished five-grade motor oil, the light and heavy components are blended in amounts ranging from about to parts of the light component with from about 15 to 30 parts of the heavy component on a volume basis. A typical base oil would have a maximum of about 10 volume percent of the oil boiling below 725F. with the following viscometric properties:

2.0 centistokes Minimum Viscosity at 300F.

4.0 centistokes Minimum Viscosity at 210F.

The additives to be added to the base oil formulation in order to obtain a finished crankcase oil with the proper SAE specification are those that are available commercially, such as the A.P.l. Service S.E.-type additives. 1n the instant formulation, two additives which are preferred to be combined with the base oil are a viscosity index improver and a multi-functional additive which is also a detergent-dispersant-inhibitor-type additive. A representative additive of the former type is polymethylmethacrylate which typically may have a specific gravity of about 0.9, a viscosity at 210F. of about 4200 SSU, and viscosity at F. of about 63,000 SSU with a pour point of +25F. A representative additive of the latter type typically has a specific gravity of 0.95, a viscosity at 210F. of 156 SSU and contains minor quantities of magnesium, nitrogen, phosphorus, sulfur and zinc. Chemically this additive contains zinc dialkyl dithiophosphate and calcium alkyl phenates as oxidation inhibitors, a succinimide as an ashless dispersant and magnesium sulfonate as a detergent.

A typical oil formulation falling within the limits specified hereinabove is illustrated by the following example:

EXAMPLE In a tank maintained at F. and fitted with a continuous stirrer were blended 1335 gallons of a viscosity index improver consisting of polymethylmethacrylate 19,110 gallons of a l-lVl 85 oil consisting of 12.9 vol ume percent of a fraction of a dewaxed dearomatized, catalytically cracked stock having a 210F. viscosity of 2.85 centistokes and a 100F. viscosity of 11.5 centistokes, and 87.1 volume percent of a fraction having a 210F. viscosity of 3.89 centistokes and a 100F. viscosity of 19.01 centistokes. In a separate tank at 140F. were mixed, with continuous stirring, 3450 gallons of SEN 140 oil, 1320 gallons of SEN 750 oil, 1335 gallons of the above viscosity index improver and 3450 gallons of a detergent-dispersant-inhibitor additive comprising a mixture of a zinc dialkyl dithiophosphate, a calcium alkyl phenate, magnesium sulfonate and a succinimide. To this mixture were added the above blend of l-lVl 85 oil and viscosity index improver. The final oil blend fulfilled the necessary requirements for a five-grade SAE 5W-40 motor oil.

TABLE 1 Cat Cracked SEN Dewaxed Stocks SEN 100 SEN 140 750-800 Viscosity 300F., Cs 1 5 2.0 2.3 5.1 Viscosity 210F.. Cs 2.85 3.89 5.0 14.23 Viscosity I()()F., Cs 11.5 19.01 21.75 30.37 160.0 Viscosity F.. po1scs 2.8 5.5 6.15 l 1.1 100.() Distillation 0F., 760 mm* lBP 622 690 700 719 722 2 647 722 735 865 5 652 714 730 748 892 662 721 733 753 904 670 73 l 740 762 922 50 693 750 753 785 964 90 732 790 789 835 1035 95 747 812 808 860 1032 E.P. 770 816 818 880 'ASTM D-l 160 TABLE 11 Effect of 725F. Component on Oil Consumption of Finished Oil Oil Type 10W-40 10W 5W-40 5W-4O 5W-4O 5W-40 725F. Component, 0 17 34.5 20 12 9 Vol.71* Oil Consumption, 2.28 4.0 4.43 3.42 2.0 2.94 Oz/Hr.

*ASTM D-1160 We claim: extracted neutral 011 of about 140 SSU viscosity 1. A blended base oil composition for. use in a fiveat 100F., and grade SAE 5W-40 motor 011 comprising a blend ofthe- 2. from about 16 to 28 parts by volume ofa solvent following mineral oil components: extracted neutral oil of about 750 SSU viscosity,

component (A) which consists essentially of a mixat 100F.,

ture of said component (A) having a minimum viscosity at 1. from about 70 to 85 parts by volume ofa solvent 300F. of 2.5 centistokes, a minimum viscosity at extracted neutral oil of about 100-150 SSU vis- 210F. of 6.0 centistokes, a maximum viscosity of 0F. cosity at 100F., and of 20.0 poises, with zero percent of the oil boiling 2. from about 15 to 30 parts by volume of a solvent below 725F; and I extracted neutral oil of about 700-800 SSU viscomponent (B) which consists essentially of a blend cosity, at 100F., of dewaxed oils obtained from an essentially arosaid component (A) having a minimum viscosity at maticfree catalytically cracked stock, said blend 300F. of 2.5 centistokes, a minimum viscosity at having a minimum viscosity of 210F. of 3.2 centi- 210F. of 6.0 centistokes, a maximum viscosity at 0F. stokes, a maximum viscosity at 01 of 5,9 poises of 20.0 poises, with little or none of the oil boiling and a maximum of 15 percent by volume of the debelow 725F.; and waxed oils boiling below 725F.;

component (B) which consists essentially of l-lVl and wherein component (B) comprises from about -90 dewaxed oil obtained from an essentially to percent by volume of the total base oil composiaromatic-free catalytically cracked stock said de- 5 tion. waxed oil having a minimum viscosity at 210F. of 3. The blended base oil composition of claim 1 3.2 centistokes, a maximum viscosity at 0F. of 5.9 wherein component (B) consists essentially of a blend poises and a maximum of 25 percent by volume of of the dewaxed oil boiling below 725F., 1. from about 5 to 18 parts by volume of a fraction and wherein component (B) comprises from about 70 60 of a dewaxed, catalytically cracked stock having to percent by volume of the total base oil composia viscosity at 210F. of from about 2.8 to 2.9 cention. tistokes, a maximum viscosity at 0F. of 2.9 2. A blended base oil composition of claim 1 for use poises, and a maximum of 80 percent by volume in a five-grade SAE 5W-40 motor oil comprising a of said oil fraction boiling below 725F.; and blend of the following mineral oil components: 5 2. from about 82 to parts by volume of a fraccomponent (A) which consists essentially of a mixture of 1. from about 72 to 84 parts by volume of a sol ent tion from said catalytically crackedstock having a viscosity at 210F. of from 3.8 to 4.0 centi- L flemmaza um viscosity at -s 51 -9 and a maximum of 15 percent by volume of said oil fraction boiling below 725F.

4. The blended base oil composition of claim 2 wherein the volume ratio of component (B) to component (A) is about 4 to 1.

5. In a five-grade SAE 5W-4O motor oil with excellent consumption properties and thermal and wear stability having a measured viscosity at F. not to exceed 12.0 poises, a minimum viscosity at 210F. of 14.7 centistokes, a minimum viscosity at 300F. of about 6.5 centistokes, and wherein no more than 15 percent by volume of the oil boils below 725F., comprising a multifunctional detergent-dispersant-inhibitor additive, a viscosity index improver and a base oil composition the improvement comprising using as a base oil a blend of the following mineral oil components:

component (A) which consists essentially of a mixture of l. from about 70 to 85 parts by volume of a solvent extracted neutral oil of about 100-150 SSU viscosity at 100F., and 2. from about 15 to 30 parts by volume ofa solvent extracted neutral oil of about 700-800 SSU viscosity at 100F., said component (A) having a minimum viscosity at 300F. of 2.5 centistokes, a minimum viscosity at 210F. of 6.0 centistokes, a maximum viscosity at 0F. of 20.0 poises with little or none of the oil boiling below 725F.; and

component (B) which consists essentially of l-lVl 75-90 dewaxed oil obtained from an essentially aromatic-free catalytically cracked stock, said dewaxed oil having a minimum viscosity at 210F. of 3.2 centistokes, a maximum viscosity at 0F. of 5.9 poises and a maximum of 25 percent by volume of the dewaxed oil boiling below 725F.;

and wherein component (B) comprises from about 70 to 85 percent by volume of the total base oil composition.

6. The five-grade motor oil of claim SWherein no more than 12 percent by volume of the boil boils below 725F. and component (A) consists essentially of 1. from 72 to 84 parts by volume of a solvent extracted neutral oil of about 140 SSU viscosity at 100F., and 2. from about 16 to 28 parts by volume ofa solvent extracted neutral oil of about 750 SSU viscosity at 100F., with zero percent of the oil boiling below 725F.; and component (B) which consists essentially of a blend of dewaxed oils obtained from an essentially aromaticfree catalytically cracked stock; said blend having a maximum of 15 percent by volume of the dewaxed oils boiling below 725F.; wherein component (B) comprises to percent by volume of the total base oil composition.

7. The five-grade SAE 5W40 motor oil composition of claim 4 wherein component (B) consists essentially of a blend of 1. from about 5 to 18 parts by volume of a fraction of a dewaxed, catalytically cracked stock having a viscosity at 2 10F. of from about 2.8 to 2.9 centistokes, a maximum viscosity at 0F. of 2.9 poises, and a maximum of 80 percent by volume of said oil fraction boiling below 725F.; and

2. from about 82 to parts by volume of a fraction from said catalytically cracked stock having a viscosity at 210F. of from 3.8 to 4.0 centistokes, a maximum viscosity at 0F. of 5.5 poises and a maximum of 15 percent by volume of said oil fraction boiling below 725F.

8. The composition in claim 5 wherein said viscosity index improver is polymethylmethacrylate and said multifunctional detergent additive comprises a mixture of zinc dialkyl dithiophosphate, a calcium alkyl phenate, a succinimide and magnesium sulfonate.

9. An HVl 75-90 dewaxed oil having an average viscosity of 75 to about 90 SSU at F. obtained from an essentially aromatic-free catalytically cracked stock, said dewaxed oil having a minimum viscosity at 210F. of 3.2 centistokes, a maximum viscosity at 0F. of 5.9 poises and a maximum of 25 percent by volume of the dewaxed oil boiling below 725F.

10. The HVl 75-90 dewaxed oil of claim 9 wherein a maximum of 15 percent by volume of the dewaxed oil boils below 725F.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Q PATENT NO. 3 73 455 DATED March 25 1975 1 Richard D. Schieman It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below: 0

Column 5 Table I SEN 100 SEN 140 and SEN 750-800 should read as follows SEN 100 SEN 140 SEN 750-800 Signed and Scaled this 7 Fifth Day of October 1976 [SEAL] Arrest:

RUTH c. MASON c. MARSHALL DANN Arresting Officer (umnrissioner of Parents and Trademarks

Claims

1. A BLENDED BASE OIL COMPOSITION FOR USE IN A FIVE-GRADE SAE 5W-40 MOTOR OIL COMPRISING A BLEND OF THE FOLLOWING MINERAL OIL COMPONENTS: COMPONENT (A) WHICH CONSISTS ESSENTIALLY OF A MIXTURE OF

1. FROM ABOUT 70 TO 85 PARTS BY VOLUME OF A SOLVENT EXTRACTED NEUTRAL OIL OF ABOUT 100-150 SSU VISCOSITY AT 100*F., AND

2. FROM ABOUT 15 TO 30 PARTS BY VOLUME OF A SOLVENT EXTRACTED NEUTRAL OIL OF ABOUT 700-800 SSU VISCOSITY, AT 100*F., SAID COMPONENT (A) HAVING A MINIMUM VISCOSITY AT 300*F. OF 2.5 CENTISTOKES, A MINIMUM VISCOSITY AT 210*F. OF 6.0 CENTISTOKES, A MINIMUM VISCOSITY AT 0*F. OF 20.0 POISES, WITH LITTLE OR NONE OF THE OIL BOILING BELOW 725*F.; AND COMPONENT (B) WHICH CONSISTS ESSENTIALLY OF HVI 75-90 DEWAXED OIL OBTAINED FROM AN ESSENTIALLY AROMATIC-FREE CATALYTICALLY CRACKED STOCK SAID DEWAXED OIL HAVING A MINIMUM VISCOSITY AT 210*F. OF 3.2 CENTISTOKES, A MAXIMUM VISCOSITY AT 0*F. OF 5.9 POISES AND A MAXIMUM OF 25 PERCENT BY VOLUME OF THE DEWAXED OIL BOILING BELOW 725*F., AND WHEREIN COMPONENT (B) COMPRISES FROM ABOUT 70 TO 85 PERCENT BY VOLUME OF THE TOTAL BASE OIL COMPOSITION.

2. from about 82 to 95 parts by volume of a fraction from said catalytically cracked stock having a viscosity at 210*F. of from 3.8 to 4.0 centistokes, a maximum viscosity at 0*F. of 5.5 poises and a maximum of 15 percent by volume of said oil fraction boiling below 725*F.

2. from about 16 to 28 parts by volume of a solvent extracted neutral oil of about 750 SSU viscosity at 100*F., with zero percent of the oil boiling below 725*F.; and component (B) which consists essentially of a blend of dewaxed oils obtained from an essentially aromatic-free catalytically cracked stock; said blend having a maximum of 15 percent by volume of the dewaxed oils boiling below 725*F.; wherein component (B) comprises 70 to 80 percent by volume of the total base oil composition.

2. from about 15 to 30 parts by volume of a solvent extracted neutral oil of about 700-800 SSU viscosity at 100*F., said component (A) having a minimum viscosity at 300*F. of 2.5 centistokes, a minimum viscosity at 210*F. of 6.0 centistokes, a maximum viscosity at 0*F. of 20.0 poises with little or none of the oil boiling below 725*F.; and component (B) which consists essentially of HVI 75-90 dewaxed oil obtained from an essentially aromatic-free catalytically cracked stock, said dewaxed oil having a minimum viscosity at 210*F. of 3.2 centistokes, a maximum viscosity at 0*F. of 5.9 poises and a maximum of 25 percent by volume of the dewaxed oil boiling below 725*F.; and wherein component (B) comprises from about 70 to 85 percent by volume of the total base oil composition.

2. from about 16 to 28 parts by volume of a solvent extracted neutral oil of about 750 SSU viscosity, at 100*F., said component (A) having a minimum viscosity at 300*F. of 2.5 centistokes, a minimum viscosity at 210*F. of 6.0 centistokes, a maximum viscosity of 0*F. of 20.0 poises, with zero percent of the oil boiling below 725*F; and component (B) which consists essentially of a blend of dewaxed oils obtained from an essentially aromatic-free catalytically cracked stock, said blend having a minimum viscosity of 210*F. of 3.2 centistokes, a maximum viscosity at 0*F. of 5,9 poises and a maximum of 15 percent by volume of the dewaxed oils boiling below 725*F.; and wherein component (B) comprises from about 70 tO 80 percent by volume of the total base oil composition.

2. A blended base oil composition of claim 1 for use in a five-grade SAE 5W-40 motor oil comprising a blend of the following mineral oil components: component (A) which consists essentially of a mixture of

2. from about 15 to 30 parts by volume of a solvent extracted neutral oil of about 700-800 SSU viscosity, at 100*F., said component (A) having a minimum viscosity at 300*F. of 2.5 centistokes, a minimum viscosity at 210*F. of 6.0 centistokes, a maximum viscosity at 0*F. of 20.0 poises, with little or none of the oil boiling below 725*F.; and component (B) which consists essentially of HVI 75-90 dewaxed oil obtained from an essentially aromatic-free catalytically cracked stock said dewaxed oil having a minimum viscosity at 210*F. of 3.2 centistokes, a maximum viscosity at 0*F. of 5.9 poises and a maximum of 25 percent by volume of the dewaxed oil boiling below 725*F., and wherein component (B) comprises from about 70 to 85 percent by volume of the total base oil composition.

3. The blended base oil composition of claim 1 wherein component (B) consists essentially of a blend of

5. In a five-grade SAE 5W-40 motor oil with excellent consumption properties and thermal and wear stability having a measured viscosity at 0*F. not to exceed 12.0 poises, a minimum viscosity at 210*F. of 14.7 centistokes, a minimum viscosity at 300*F. of about 6.5 centistokes, and wherein no more than 15 percent by volume of the oil boils below 725*F., comprising a multifunctional detergent-dispersant-inhibitor additive, a viscosity index improver and a base oil composition the improvement comprising using as a base oil a blend of the following mineral oil components: component (A) which consists essentially of a mixture of

6. The five-grade motor oil of claim 5 wherein no more than 12 percent by volume of the boil boils below 725*F. and component (A) consists essentially of

7. The five-grade SAE 5W-40 motor oil composition of claim 4 wherein component (B) consists essentially of a blend of

9. An HVI 75-90 dewaxed oil having an average viscosity of 75 to about 90 SSU at 100*F. obtained from an essentially aromatic-free catalytically cracked stock, said dewaxed oil having a minimum viscosity at 210*F. of 3.2 centistokes, a maximum viscosity at 0*F. of 5.9 poises and a maximum of 25 percent by volume of the dewaxed oil boiling below 725*F.

10. The HVI 75-90 dewaxed oil of claim 9 wherein a maximum of 15 percent by volume of the dewaxed oil boils below 725*F.