Future European passenger car lubricants for low emission engines

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Future European passenger car lubricants for low emission engines

Stunnenberg, F. / Leeuwen, J.A.v. / Boffa, A.B.

Introduction of emission control devices to meet future emission legislation in passenger car engines is likely to result in decreased sulfur, phosphorus and sulfated ash levels in future PCMO/PCDO lubricants. As fuel sulfur levels decrease, the relative contribution of lubricant derived sulfur to the exhaust stream increases. However, at typical passenger car oil consumption levels, the lubricant derived sulfur remains a relatively insignificant factor. Future lubricant sulfur requirements can be met by moving to low sulfur base stocks. The future phosphorus requirements are set by the proposed ILSAC GF-4 limits. It is demonstrated that ZnDTP levels can be significantly reduced without impact on engine wear in the OM 602A and Sequence IVA tests. Sulfated ash levels can be reduced as part of the functionality of metallic detergents can be replaced by ashless dispersants. However, this may decrease fluoro elastomer seal compatibility. There should be willingness within the industry to critically examine and if necessary modify other aspects of future engines besides fuels and lubricants. Viscosity control of low emission lubricants may be ensured by a proper selection of anti-oxidants. Excellent viscosity control has been shown in a double length Sequence IIIF engine test. Good performance of lubricants meeting the assumed future levels for sulfur, phosphorus and sulfated ash has been shown in ACEA and API gasoline and diesel engine tests versus ACEA A3/B3/B4, ILSAC GF-3/4 and certain OEM performance limits.