Last Updated:

4 Best Oil Additives to Care for Older Engines

Older engines and those that have clocked a fairly high mileage require special care to ensure they maintain the same level of performance that they had when they were newer. Doing so requires only the best type of care there is and this can be obtained by ensuring that what is fed to the engine is of good quality.

Here’s what you ought to know:

Besides having the best engine oil for the engine, it is a good idea to invest in oil additives that understand the most important needs of the engine to ensure that it performs as expected.

The benefits of using the best oil additives for your older/high mileage engine are numerous:

Not only do they enhance performance and maintain the youthful state of the engine but they also ward off any issues that stem from having an older engine. Such issues include, but are not limited to, unwanted engine breakdowns, corrosion of internal engine components, worn-out gaskets and seals, and engine knocking.

There are countless oil additives that claim to be on top of the table when it comes to caring for older engines. This is why we have compiled a list of only the best oil additives to ensure your choice is a worthy investment.

Best Oil Additives for Older Engines – Comparison Table

Best Oil Additives for Older Engines – Reviews

Nanolube Engine Oil Additive

Quick Specs
  • Rating: 4.9 / 5
  • Brand: Nanolube
Check Price on Amazon

As we get older, our organs are subjected to more work and as a result, require eventual detoxification. The same goes for the engines in our cars. With increased use, it is time to give them the detox treatment they deserve if they are to last longer. No additive does this job better than Nanolube.

Specially formulated to function perfectly on both diesel and gasoline engines, Nanolube is capable of mixing with all grades of engine oil without a fuss. It eliminates dry starts by adhering to metal surfaces to avoid dripping off.

A good oil additive is one that can take care of overheating issues in your engine. With Nanolube, your engine is safe from this issue thanks to its cooling effect.

Trust Nanolube to make your old engine work like new and stop the aging process entirely. This will help save you money in the long run by avoiding unwarranted repairs while maintaining the same level of performance.


  • Suitable for all engine types
  • Mixes well with most grades of engine oil
  • Improves efficiency
  • Economically viable
  • Reduces engine emissions


  • Can get too thick to be filtered in some cases

Marvel Mystery Oil

Quick Specs
  • Rating: 4.7 / 5
  • Brand: Marvel
Check Price on Amazon

Marvel Mystery Oil fortifies the base properties of your basic motor oil, whether traditional or synthetic, by increasing its ability to prevent valve sticking and clutter by breaking down the harmful deposits of carbon and sludge.

It will prevent sludge build-up in newer engines and remove built-up sludge in the older ones. This helps the engine run smoothly and efficiently. It, therefore, functions well in improving the performance of your older engine.

Using this oil additive improves the performance of all your valves and ultimately improves your overall fuel economy. This makes it one of the best oil additives for older engines as it is not only pocket-friendly but also very efficient.


  • Works perfectly in most motors
  • Rejuvenates gasoline
  • Fairly cheap


  • Can plug fuel filter
  • It is not compatible with most motor oils

Slick 50 Recharged was specially formulated for engines that have experienced a loss in performance due to friction and wear, oil consumption and leaks, smoking and sludge build-up. With this special formula, your high mileage engine is guaranteed to run just like a new one.

This additive works best with 10W-30 motor oil and is intended to reduce your engine’s emissions while maximizing fuel economy. Slick 50 also increases lubricity in your engine thus helping minimize the heat that would otherwise be produced due to friction.

Slick 50 is capable of stopping leaks in your engine by revitalizing those old seals and swelling them. This is also made possible by the emission system shield. In addition, the powerful detergents in this formula remove the sludge that is already present and prevent the formation of any future build-up.


  • Improves performance
  • Stops leaks
  • Increases fuel economy
  • Increases lubricity
  • Enhances emission system durability


  • Not suitable for most grades of oil

This high viscosity formula, complete with anti-wear agent ZDDP, is specially formulated to help fight metal-to-metal friction by providing a thicker cushion between moving engine parts.

It is excellent for all car types and is guaranteed to help rejuvenate your worn out seals and gaskets. Aside from that, STP is capable of stopping engine leaks, noise, and smoking. This makes it great for high mileage engines and old engines as these are problems they are most likely to encounter.


  • Helps stop knocking and leaks
  • Suitable for all engine types
  • Compatible with all oils
  • Improves lubricity


  • Requires continuous use as it is a treatment rather than a one time fix


If you are a user of an older engine, you should consider handling it with care to avoid extensive damage happening to it. Being older does not mean it cannot perform to its maximum. All you have to do is maintain it the right way.

Invest in a high-quality oil additive for your older engine and see your engine regain its youthfulness. Receive all the power and performance capabilities it has to offer with a fix that is as simple as an efficient oil additive.

You might also like