THE ENGINE OIL MARKET
Modern 20W-50 lubricants are unlikely to possess the same compositions as those blends of 30 or more years ago. Should you own a historic vehicle, you might have noticed that 20W-50 prices match those of modern oils in some cases. One explanation might be reduced economies of scale, but consider also that discerning classic car owners are prepared to pay more for peace of mind. Naturally, retailers are happy to oblige...
While certain oils take advantage of modern technology to improve their formulations for older vehicles, buy with care. Many classic car oil blenders cite the importance of increased ZDDP (Zinc Dialkyl Dithiophosphate) levels, which were reduced over the 1990s because they damaged catalysers. Additionally, modern engine design enhancements, such as rolling rockers replacing flat tappets, mean that they are less reliant on ZDDP as an anti-wear additive. Duckhams argues that ZDDP for older engines is effective only at certain concentrations and advises CM readers not to rely solely on classic oil with the ‘most’ ZDDP, because other factors are just as relevant, such as a decent base oil quality that ensures the anti-wear additives work effectively.
For more mainstream vehicles, Adrian Hill, automotive product manager at Morris Lubricants of Shrewsbury, reports that demand for 10W-40 (in both mineral and semisynthetic) blends are in decline. If you own an older car that uses 10W-40 or 20W-50, the API/ACEA specifications will give you an idea of its performance levels, meaning that you can compare different oils with the same viscosity.
Shell confirms that 5W-30 has become the most popular viscosity in north-west Europe. However, all 5W-30s are not created equal and manufacturerspecific oils are considered normal. This has resulted in a huge range being available – Adrian says that up to a dozen 5W-30 oils were in Morris’ range at one time but, unsurprisingly, oil tech does not stand still.
While many car manufacturers recommend that you use a certain brand, the specification provided is even more important. Do your research carefully.