Ethyl Petroleum Additives, Inc.

Julia C Poat

Graeme M Wallace

David K Walters

Ian MacPherson

In a motor vehicle, especially a heavy duty motor vehicle, having a transmission equipped with at least one cone-type synchronizer and an axle or differential gearing, the same lubricant is used for both such mechanisms. The lubricant has a viscosity grade level of from SAE 75W90 to SAE 85W140 and comprises base oil containing at least (i) Mannich base ashless dispersant; (ii) metal-free, sulphur-containing antiwear and/or extreme pressure agent; (iii) metal-free, phosphorus-containing and nitrogen-containing antiwear and/or extreme pressure agent; and (iv) overbased alkali or alkaline earth metal carboxylate, sulphonate or sulphurized phenate having a TBN of at least 145. The lubricant contains at most, if any, 100 ppm of metal as one or more metal-containing additive components other than (iv).

Use of transmission and gear oil lubricants having enhanced friction

The frictional properties of gear oils are improved by including at least one overbased alkali or alkaline earth metal carboxylate, sulphonate or sulphurized phenate having a TBN of at least 200 in a gear oil which comprises: oil of lubricating viscosity at least 80% by volume of which is mineral oil, synthetic ester oil or a mixture thereof; Mannich base ashless dispersant; metal-free, sulphur-containing antiwear and/or extreme pressure agent; and metal-free, phosphorus-containing and nitrogen-containing antiwear and/or extreme pressure agent. The resultant gear oils exhibit excellent performance when used in synchromesh-based transmissions.

Growing community of inventors

Wokingham, United Kingdom

Julia C Poat