50 mm 2 sec at 40 u00b0 c 6 preferably the bearing grease composition further comprises one or more thickening agents 7 the bearing grease composition as in any of the above described aspects 1 to 6 comprising further lubricants and or additives the carbonate compound can be used alone or as mixtures thereof the present invention will now be described in more detail below by referring to the following examples but the invention should not be limited thereto those examples are the preparation example of the typical bearing grease composition consisting of component a and component b that is in the formula i r is the branched alkyl group represented by the following formula iv and r u2032 is the branched alkyl group represented by the following formula v this carbonate is hereinafter referred to as u201c carbonate oil a u201d alone or a mixed oil of a carbonate containing commercially available organic carbonate having different structure of an alkyl group cycrant t 394 trade name a product of mitsui petrochemical industries ltd this ester is hereinafter referred to as u201c carbonate ester oil b u201d and the carbonate ester oil a was mixed with lithium stearate and or lithium 12 hydroxystearate in the proportions as shown in table 1 such that the sum of those was 100 mass the resulting mixture was heated to 220 230 u00b0 c while stirring until the whole of mixture became.