Over the last 100 years, engine oil formulations have come a long way, along with advances in engine design during these years. Today’s engines are specifically designed with highly advanced devices whose job is to control and regulate emissions.
This has lead to a huge reduction in the use of zinc dialkyl dithiophosphate (ZDDP) content in engine oil. If there’s too much phosphorous and ZDDP, additives can hurt the car’s catalytic converter and hinder its usefulness. Today, we’ll discuss the characteristics to look for in the best oil for classic cars.
The Importance of Zinc Additives for Classic Cars
Zinc additives historically have been effective anti-wear agents and nowhere is this more important than in classic and modified performance cars that utilize flat-tappet camshafts, custom lifters, and rocker arms for enhanced performance.
This reduction in zinc in modern-day engine oils makes them far less effective and useful in classic and modified performance cars.
When designing automotive engines, there are two choices in camshafts: flat-tappet and roller. The lifter, or tappet, on a flat-tappet camshaft is, of course, flat and must have a film of oil to keep its surface separated from the camshaft lobe.
Protecting Flat-Tappet Camshafts
Flat-tappet camshafts can generate a tremendous amount of heat due to the high friction caused by the surfaces sliding quickly against each other. The only thing stopping the cam lobe and lifter from welding together is the critical oil film barrier separating the two surfaces.
Engine valve operation can be adversely affected if the flat-tappet cam is unduly worn down due to the friction between the cam lobe and lifter.
If the flat-tappet cams are unable to effectively lift the engine valves sufficiently so that they can adequately charge the chamber for ignition or adequately release exhaust fumes, then engine efficiency and power go into decline.
Unlike other areas of the engine, the lifters and cam lobes are splash lubricated, thus adding more strain on the anti-wear additives in the engine oil.
The other type of camshafts used in engine design are roller cams. They are different from flat-tappet cams because they function with a rolling contact area rather than a sliding contact area.
They are more expensive but are the chosen camshaft in most modern-day engine designs. They can be retrofitted into high-performance hot rod engines and classic cars.
The best oil for classic cars is synthetic motor oil with high volumes of ZDDP, so as to provide maximum protection for flat-tappet cams, lifters, rockers, and other areas of the engine that would be exposed to wear.
By choosing to use synthetic engine oil for older cars formulated with a high content of zinc and phosphorous, the classic car engine will get extra protection for any critical splash lubricated engine parts.
Before going further, let’s talk about the difference between conventional petroleum oils and synthetic engine oils.
You would think that when looking for the best oil for classic cars, we would gravitate towards petroleum-based oils since those were the type of oils available during the classic car era.
Before we assume this, let’s keep an open mind and briefly explain the differences between the two types of oils. The simple fact is, conventional petroleum oils are refined, whereas synthetic oil is man-made and engineered. Ultimately, this makes synthetics the better buy.
When refining crude oil, the process is unable to remove many of the unwanted contaminants and impurities inherent in petroleum-based crude oils. These unnecessary impurities take away the oil’s ability to lubricate effectively.
These contaminants eventually contribute to deposit, varnish, and sludge formation. Without a doubt, these contaminants will be of great detriment to your finely restored and built classic car engine.
Finding the Best Oil for Classic Cars
On the flip side of this engine oil comparison, we have 100% synthetic engine oils, which are engineered in the laboratory using an advanced processing method that removes all impurities.
These man-made synthetic base stock oils are pure, with uniform molecular structures, and are specifically designed to deliver in particular lubricating applications.
These highly engineered pure synthetic base stocks can withstand extremely high temperatures and the most severe operating conditions that any classic car, muscle car, or high-performance hot rod can throw at them.
Your beloved classic car demands only the best possible engine oil available. You want to maintain cleanliness, minimize wear and feel confident that during the running of your prized possession, your engine will be completely protected.
Using synthetic oil in classic cars has become more of the norm today than ever before.
The next critical area that is not only important but a necessity, is protecting your classic car’s engine from corrosion and rust. Typically, classic cars are kept in storage the majority of the time and they’re driven rather infrequently. Most driving takes place during the hot summer months.
There’s a reason your car is called a classic car. There are very few of them left running, especially in the beautiful condition you’ve restored your prized possession to.
Without sounding presumptuous, most would agree that providing maximum protection during extended periods of storage would be a priority for most classic car owners.
Stop Your Engine from Rusting During Storage
When researching the best oil for classic cars, look for one that has been engineered with high levels of corrosion and rust inhibitors. As these additive names suggest, their task is to protect the metal from rust and corrosion when exposed to moisture.
Because of the changes in seasons, there is a likelihood of moisture presenting itself to your stored engine components. This can especially be true when the weather is highly humid.
If an engine oil has been specifically engineered with robust volumes of rust and corrosion inhibitors, then it’s a good bet such a classic car oil will deliver the type of protection your classic car needs during long term storage.
For those storing a covered classic car or hot rod in a damp garage, a synthetic oil blended with higher levels of rust and corrosion inhibitors is a definite requirement.
In summary, when looking for the best oil for classic cars, only look for one that has been formulated with higher volumes of ZDDP to protect against unnecessary wear to your engine’s flat-tappet cams, lifters, rockers, and other critical parts.
Additionally, when researching what you’re going to put into your prized possession, look to see if such oil was engineered with high levels of rust and corrosion inhibitors so that it protects your engine during long term storage.
Finally, don’t question whether synthetic oil in classic cars is a good thing.
As we’ve already stated earlier, a synthetic-based engine oil would be highly beneficial to any vintage classic car, because it will withstand extreme heat, it will offer reduced wear, and when you finally get around to taking your stored classic car out for a summertime cruise, synthetic oils provide instant protection during cold dry starts.
It has been found that 80% of engine wear occurs during cold dry starts. Since your engine has been sitting for a long time, you want those parts immediately protected with a lubricating film, and only a synthetic-based engine oil can provide that kind of immediate protection, thus minimizing this unnecessary wear during dry startups.