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What oils should you use in classic cars?

Passenger Car

Classic or vintage vehicles can be the pride of any car collector’s fleet. While simply showcasing a stationary vehicle involves a certain amount of care to preserve its appearance, owners of vintage models who wish to run their cars or parade them at exhibitions and shows must keep their innerworkings in good working order.

It is understood that engines in modern cars have advanced considerably over time to deliver enhanced performance, greater cleanliness, and lower pollution output. To ensure cutting-edge engines are cared for, lubrication solutions have also improved in step, becoming more complex. As a result, most modern engine oils cannot provide suitable lubrication for classic cars.

Fortunately, many leading lubrication manufacturers have produced 20W/50 multi-grade oils that are specially formulated for use in classic cars. However, another option open to owners of vintage vehicles is to use a standard 20W/50 oil along with a ZDDP additive. Read on to find out more.

Understanding modern oil formulas

As modern API-grade SMI engine oils are no longer permitted to include substantial amounts of zinc dialkyldithiophosphate (or ZDDPfor short) in their formulation, it is imperative to employ an oil specially designed for classic cars to prevent damage to the camshaft lobes and tappets which only ZDDP can mitigate.

Another problem is that modern engine oil formulas are mainly designed to deliver lubrication rather than a specific amount of corrosion prevention. Corrosion is a critical consideration for many classic cars, as they are often subjected to extended periods in storage and little use.

Classic vehicle oils are designed to contain the ideal amount of ZDDP (between 1400 and 1500 PPM), but also include special additives to stop seal contraction over long-term storage, such as detergents that neutralise acids and defend against corrosive forces, and rust dispersants that maintain damaging contaminants in liquid suspension.

Alternatives to using engine oils designed for classic cars

As engine oil that contains the ZDDP required by classic cars is no longer typically available from most stores selling automotive supplies, an acceptable alternative can be to use a standard 20W/50 engine oil blend with a specific ZDDP additive to obtain the optimum lubrication required by the camshaft lobes and flat tappets in classic car’s engine.

Finally, when employing an additive, it is vital to follow the manufacturer’s instructions on the bottle to the letter as too much ZDDP added is as equally undesirable as using too little.

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