in order to determine the effect of the lowering of the friction coefficient as well as the wear by the grease composition according to the disclosure , srv tests are carried out using an optimol instruments srv tester . flat disc lower specimens made of the 100cr6 standard bearing steel from optimol instruments prüflechnik gmbh , westendstrasse 125 , munich , properly cleaned using a solvent are prepared and contacted with the grease composition to be examined . the srv test is an industry standard test and is especially relevant for the testing of greases for the cvj . the test includes an upper ball specimen with a diameter of 10 mm made from 100cr6 bearing steel reciprocating under load on the flat disc lower specimen indicated above . in tests for mimicking tripod joints , a frequency of 40 hz with an applied load of 500 n were applied for 60 minutes ( including running - in ) at 80 ° c . the stroke was 3 . 0 mm . the friction coefficients obtained were recorded on computer . for each grease , the reported value is an average of two data at the end of tests in two runs . wear is measured using a profilometer and a digital planimeter . by using the profilometer , a profile of the cross section in the middle of the worn surfaces can be obtained . the area ( s ) of this cross section can be measured by using the digital planimeter . the wear quantity is assessed by v = si , where v is the volume of the wear and i is the stroke . the wear rate ( wo is obtained from w r = v / l [ μm 3 / m ], where l is the total sliding distance in the tests . for the running - in , it is started with an applied load of 50 n for 1 minute under the above - specified conditions . afterwards , the applied load is increased for 30 seconds by 50 n up to 500 n . further , tests regarding the properties of a rubber boot and a tpe - boot , respectively , equipped with a grease composition in accordance with the present disclosure according to example c4 compared with two commercial grease compositions a and b were carried out with respect to the change of a hardness ( shore d ) and the percentage change of tensile , elongation , and volume before and after a heat ageing of the boot material immersed in a grease at 125 ° c . for 336 hours . said values are measured in accordance with iso 868 ( shore d ), iso 37 ( tensile change and elongation change ), and iso 2781 ( volume change ). the commercial greases used in comparative examples a and b are axel casx 51646 , obtained from axel christiernsson b . v ., heijningen , netherlands , ( comparative example a ) and super grease 2 obtained from tianjin lubricant and grease co . ltd . ( jinzhi ), sinopec corp ., tianjin , p . r . china ( comparative example b ). the following substances are used in the examined grease compositions in accordance to the present disclosure . the base oil composition used has a kinematic viscosity of about 165 mm 2 / s at 40 ° c . and about 16 mm 2 / s at 100 ° c . the base oil blend may be a mixture of one or more paraffinic oils in a range between about 10 to about 60 % by weight , preferably about 20 to 40 % by weight , one or more naphthenic oils in a range between about 30 to about 80 % by weight , preferably about 55 to about 80 % by weight , and , if necessary , one or more poly - α - olefins ( pao ) in a range between about 5 to about 40 % by weight , referred to the total amount of the oil mixture . the oil blend may further contain dos in a range between about 2 to about 10 % by weight , referred to a total amount of the oil mixture . the concrete oil blend used in the examples is made of 73 % by weight of naphthenic oil sr130 , produced by ab nyna &# 39 ; s petroleum , stockholm , sweden , 25 % by weight of paraffine oil ns650 , obtained by kuwait petroleum europoort b . v , europoort , netherlands , and 2 % by weight of dos . the naphthenic oils are selected with a range of viscosity between about 20 to about 180 mm 2 / s at 40 ° c ., paraffinic oils between about 25 to about 400 mm 2 / s at 40 ° c ., and pao between about 6 and about 40 mm 2 / s at 100 ° c . the calcium sulphonate soap used in the examples of the present disclosure is an overbased calcium sulphonate soap obtained from a reaction of overbased calcium sulphonate with a metal ratio of about 6 to 35 with 12 - hydroxystearic acid in the presence of a solvent neutral oil , calcium carbonate , isopropyl alcohol and phosphoric acid . a possible method for producing the calcium sulphonate soap used is described in u . s . pat . no . 5 , 126 , 062 . the tri - molecular molybdenum compound used in the grease compositions according to the present disclosure is a sulphur - containing tri - nuclear molybdenum compound obtainable under the trade name c9455b by lnfineum international ltd ., uk . its structure is defined in u . s . pat . no . 6 , 172 , 013 b1 . a molybdenum dithophosphate ( modtp ) sold under the commercial name sakuralube 300 ( s - 300 ) by asahi denka co . ltd ., japan , with the chemical formula 2 - ethylhexyl molybdenum dithiophosphate , diluted with mineral oil , is used . further , a solid molybdenum dithiocarbamate ( modtc solid ) sold under the trade name sakuralube 600 ( s - 600 ), produced by asahi denka co . limited , japan , or under the trade name molyvan a , produced by r . t . vanderbilt company , inc , usa , is used . further , a molybdenum dithiocarbamate sold under the trade name sakuralube 200 ( modtc s - 200 ) in the liquid state , produced by asahi denka co . limited , japan , is used , as well as a s - free and p - free organic molybdenum additive sold under the trade name s - 701 by asahi denka co . limited , japan , being a molybdenum amine complex with the general formula r 2 n — mo x oyh , as well as usual mos 2 . as a friction modifier a zinc compound additive , namely zinc dithiophosphate zndtp , sold by lnfineum international ltd ., oxfordshire , uk 1 under the trade name c9425 , is used , being a zinc dialkyldithiophosphate with primary and / or secondary alkyl groups , especially having 3 to 8 c - atoms , preferably having 4 to 5 c - atoms , diluted with mineral oil . first , the advantages of the grease composition according to the present disclosure were examined by measuring the friction coefficient and the welding load of the six different greases , as listed in table 1 : the results from the srv - measurements of the friction coefficient as well as the welding load measurements of examples a1 to a8 may be derived from fig1 . and fig2 . the lowest friction coefficient , and , however , the highest wear is measured when adding a simple mos 2 , whereas a very low wear as measured with respect to example a3 with an increased friction coefficient compared with example a1 being a grease composition not in accordance with the present disclosure only composed of the base oil and a calcium sulphonate soap . further , also examples a2 and a5 show good results with respect to the wear . in a further series of tests , the amount of the tnmos as well as of the modtc solid is amended . ten grease compositions were prepared in accordance with table 2 . in examples b1 to b3 the amount of the tnmos is amended , wherein in examples b4 to b7 the amount of modtc solid is amended . examples b8 to b10 refer to mixtures of 0 . 5 wt .-% tnmos to different amounts of modtc solid . the results from the srv measurements with respect to the friction coefficient as well as the welding load may be derived from fig3 and fig4 . example b3 shows the lowest friction coefficient , however , the results for the wear are only in the midrange of the results obtained . further , low friction coefficients were measured with respect to examples 139 to 1310 , of which example 139 shows one of the lowest wear measured . said test results show that especially combinations of different molybdenum containing compounds are preferable , and that the ranges of the molybdenum compounds used are very sensitive with respect to the friction coefficient and wear measured . in a third test series , the effect of addition of an amount of 0 . 5 wt .-% of different molybdenum containing compounds and zndtp to the amount of 1 . 5 wt .-% modtc solid is studied . the grease compositions c1 to c6 examined are defined in table 3 . the results from the srv measurements of the friction coefficient as well as the measurement of the welding load may be derived from fig5 and 6 . one may easily derive that composition c4 being a composition of 1 . 5 wt .-% of modtc solid in the solid state and the tri - nuclear molybdenum compound in an amount of 0 . 5 wt .-% is most preferred , because both the friction coefficient as well as the wear are considerably lower when compared to the results of the other compositions . finally , combinations of three molybdenum compound additives or two molybdenum compound additives together with zndtp are examined in accordance with table 4 . the amount of modtc solid is not varied . as may be derived from fig7 and 8 referring to examples d1 to d5 , the lowest friction coefficient was measured with respect to example d5 , whereas the wear was very low in examples d2 and d4 . however , due to the lowest friction coefficient , grease composition d5 being very similar to grease composition c4 appears to be advantageous . finally , measurements of the properties of boots equipped with the different greases were carried out . a grease composition in accordance with example c4 was compared with comparative examples a and b being commercially available grease compositions . the results are listed in table 5 . as may be derived from table 5 , especially in combination with boots made of tpe - material preferable properties with respect to the tensile change and elongation change were measured , endurance tests carried out with respect to example c4 show that the endurance of constant velocity joints may be enhanced up to a twofold lifetime compared to joints equipped with boots with commercially available greases such as comparative examples a and b . in summary , the grease composition in accordance with the present disclosure has an advantageous and significant influence on the friction coefficient and the wear , leading to a good extreme pressure performance . especially preferred are combinations of two or three different molybdenum containing compounds being added to the grease composition in an amount up to 3 . 5 weight % in total , of which the addition of a tri - nuclear molybdenum compound as well as a molybdenum dithiocarbamate , preferably in the solid state , in combination are most preferred .