Motor oil plays a crucial role in the preservation and performance of classic cars. For classic car owners, who often own cars with older and specific engine designs, choosing the right oil is essential to reduce wear and maintain original condition. Classic cars often require different oil properties than modern vehicles, given their construction and use.
Difference between classic and modern motor oil
Modern oils are often designed to meet the demands of today's engines, such as fuel economy and reduced emissions, but these oils are not always ideal for older engines. Classic engines often benefit from a engine oil with higher concentrations of protective additives such as zinc (ZDDP) and phosphorus, which are essential components for the lubrication of parts such as camshafts and valves.
Additives in classic motor oil
An important component in classic car oils is the additive zinc dithiophosphate (ZDDP). ZDDP is often recommended because it helps prevent engine wear. In classic car engines, especially those without roller camshafts, ZDDP provides additional protection by forming a protective layer on metal surfaces. For some classic cars, such as models from the 50s to the 70s, an oil with a ZDDP concentration of 1200 to 1400 ppm is recommended.
Viscosity and classic engines
Classic motorcycles often perform best with a higher viscosity oil, such as 20W-50. A thicker oil can better handle the wider tolerances in older engines, where modern, thinner oils can quickly leak out and provide inadequate protection. Always check the manufacturer's recommendations, but also consider your climate and driving conditions.
Refresh regularly for optimal maintenance
For classic cars, it is important to change the oil regularly, especially if the car is not used often. Old oil can contain acids and moisture, which cause corrosion. An annual change, regardless of the number of kilometers driven, is usually sufficient for a car that is not used much. Many oil manufacturers also recommend that you do not skip the filter change with every oil change to ensure optimal performance.
Which engine oil to choose?
When choosing a motor oil for classic cars it is usually advised to stick with specialist brands that are recognised within the classic car world. Companies such as Castrol Classic Oils, Millers Oils and Penrite have extensive ranges of oils that are specifically formulated for older engines and their specific requirements.
summarizing
For classic car owners, choosing the right engine oil is essential for long-lasting performance. By selecting an oil with the right additives and viscosity, and changing it regularly, the engine can remain optimally protected. Always consult a certified specialist and stay up-to-date with the manufacturer's recommendations for the best results.
Additional facts and insights
Origin of ZDDP and its importance in classic motorcycles
Zinc dithiophosphate (ZDDP) is an additive developed in the 40s to provide better protection against wear in engines, a major problem in older engine designs. For modern cars, the amount of ZDDP in oil has been reduced due to environmental regulations, but for classic engines, a higher concentration of ZDDP remains essential. ZDDP forms a protective layer on the surfaces of critical components, especially under high pressure, which is essential for maintaining engine integrity in classic cars.
Multigrade vs. monograde oil
Although modern cars almost exclusively use multigrade oil (e.g. 10W-40), some classic car owners prefer to use monograde oil in the summer. Monograde oil, which has a single viscosity (e.g. SAE 30), offers advantages for engines with larger tolerances and in warm climates. For winter months or all-round use, multigrade oil is often more suitable, as it thickens less quickly at lower temperatures and lubricates faster at start-up.
What does high viscosity do to oil pressure?
Older engines often suffer from oil pressure problems, especially when running at higher temperatures. An oil with a higher viscosity can help maintain oil pressure, because this oil drains less quickly with greater clearance between engine parts. Classics with worn bearings sometimes benefit from even thicker oil to maintain stable oil pressure.
The danger of additives without certification
While some aftermarket additives are available, it is recommended to avoid them unless they are certified for use in classic vehicles. Non-certified additives can be chemically unstable and lead to unwanted side effects such as clogging of lines or even corroding the engine. Therefore, stick with oils that are recommended for classic cars by reputable sources and manufacturers.
The effect of unleaded fuel on motor oil
Many classic cars were originally built for leaded fuel, which can have an impact on the engine. Lead acts as a lubricant, and switching to unleaded fuel can put extra pressure on the lubricating properties of the oil. Special additives or lead substitutes in the oil can be a solution in certain cases, especially for older engines that are sensitive to wear from unleaded fuel.
Biodegradable oils: a future in the classic car world?
While biodegradable oils are primarily developed for new engines, sustainable options are also emerging for classic cars. Biodegradable oils may offer future benefits for classic cars in the event of leaks. These oils are generally less toxic and can be beneficial for older engines that are prone to corrosion. For now, however, these oils are limited in availability for classic vehicles and are often still being tested for compatibility and performance.
Interesting to read how modern oils are often not suitable for older engines. I had already switched to an oil with a higher ZDDP content for my Volvo Amazon. Many more owners should know about this!
Thanks for the clear explanation about viscosity and additives! I never knew there was so much difference in the composition of oil for classic cars. This definitely helps to take better care of my old VW Beetle.
Very informative article! It is indeed an art to choose the right oil for classic cars. I have always stuck with 20W-50 for my '72 MGB and this article confirms the importance of thicker oil for older engines. Helpful tips on ZDDP too!
Interesting article.