The growing interest in classic cars and the rising number of such vehicles still on the road has led to greater awareness that they have special lubrication needs.
That, in turn, has helped create a bigger market for these products. Petronas became the latest lubricant supplier to enter it recently, when it launched the Selenia Classic line, with engine oils for passenger cars as old as the 1970s. In doing so it joined other high-profile marketers with oils designed specifically for vintage vehicles, including Motul, Total and Castrol.
Classic cars are popular in part because of what they offer as alternative investments. According to a report in the UK daily The Telegraph, the asset class has expanded by 192 percent since 2007. Citing a report by insurers Axa Art, the first eight months of 2017 saw 7,443 classic cars sell at auctions worldwide, achieving a turnover of more than $1 billion.
Increased attention for classic cars in some countries has led to sharp increases in the number of registered vehicles. In March, the Dutch Bureau of Statistics said the fleet of cars 40 years old or older had grown 24 percent compared with 2014 to reach approximately 141,000 units.
Jerry Trentelman at The Gallery Aaldering, a Dutch business that specializes in the selling and import of high-end classics and so-called young timers, has seen the number of lubricants and oil additive retailers increase over the years, with the likes of Bardahl, Forte, Eurol and Swepco all offering such products in the Netherlands these days. Trentelman, in his capacity as chief mechanic, will for example use Engine Oil Stop Leak. This additive is designed to revitalize aged and brittle seals and o-rings. Once these swell up and regain their elasticity, they are again able to prevent fuel leaks. In short, these products enable professionals like Trentelman to better manage the suitability of a lubricant.
Engine oils for classic vehicles often come in vintage packaging - in metal cans, for example - with labels that recall those of half a century ago. Petronas new Selenia series includes three products: VS+ 15W-40, named for a French brand popular during the 1970s and formulated for model year 1970s and 1980s cars; Olio Fiat 20W-50, for cars built in the 1940s to 1960s; and Selenia Alfa 10W-40, for 1990s Alfa Romeos.
According to its promotional literature, the fluids in its old-fashioned cans are not based on old formulas. Olio Fiat is formulated with semi-synthetic base stocks, which werent defined until the 1990s. Literature for VS+ says it is designed for all engines, even those with turbochargers. Both oils are qualified for ACEA A3 and API SJ and CF oil specifications.
Apart from the basic principles of combustion, engines in older cars are very much unlike those in modern vehicles, which have higher machine tolerances and do not require the same level of anti-wear zinc dialkyl dithiophosphate lubricant additives. Additionally, a 70-year-old engine has different metallurgic features, more cog-driven components and very dissimilar oil-ways.
On top of that, older units often use so-called splash lubrication, whereby the cylinders and pistons are lubricated by rotating dippers. While not a very precise process, it does require a specific viscosity balance so that the oil can deposit an appropriate film for lubrication. In fact, the same holds true for old engines in general.
With engines of classic cars it is often difficult to ascertain how clean the internal bits are, especially with unrestored blocks. This is because the units built several decades ago, commonly referred to as veteran engines, often ran on non-detergent oils in the absence of oil filters. This product would essentially trap contaminants on surfaces.
Therefore, veteran engines of unknown condition require a monograde oil of low detergency. Too much detergent could release these contaminants, which would then create problems with combustion. Lubricants with high levels of detergent might also clear the build-up around seals and gaskets. Not only would this exacerbate the problem, it would also result in oil leaks. Once rebuilt and cleaned, pre-1950s engines can use the same oil that units from subsequent decades require: a conventional multi-grade, albeit with specific additives of an older formulation.
Take a Volkswagen Beetle, one of the best-known and best-selling cars of all time. Its engine uses both camshaft and crankshaft gears. Put differently, it doesnt have a timing belt of drive chain like modern engines. It also doesnt have an oil filter. The greater number of moving parts has a detrimental effect on the free flow of molecules in the lubricant.
This can alter the internal resistance to flow, with temperature increases as a result. This in turn affects the shear rate. For this reason, workshops for classic cars recommend a Beetle oil change every 5,000 kilometers as opposed to 30,000 km or over for modern cars.