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How Much Oil is Too Much Oil in Your Performance Car?

Will adding more oil than recommended to your high-performance car affect how it runs? Here’s the in-general answer to this question based on what engine dyno results reveal.

The Right Amount of Oil

Without a doubt, too much oil can harm your car's engine. The job of your engine oil is to lubricate various moving parts and help regulate engine temperature. However, if there's an excess amount of oil, it can lead to several issues:

  1. Aeration and foaming: When there's too much oil in the crankcase, it can cause the crankshaft to dip into the oil reservoir and whip it up. This whipping action can lead to air bubbles forming in the oil, which reduces its effectiveness in lubricating engine components.
  2. Increased pressure: Excess oil can cause higher pressure within the engine. This can lead to oil leaks, which may damage engine components or create a mess under the hood.
  3. Increased oil consumption and loss of power: In some cases, having too much oil can cause the engine to consume more oil than usual. This happens because the excess oil can be pushed past the piston rings into the combustion chamber, where it gets burned along with the fuel as well as lead to fouling of your spark plugs.

To avoid these issues, it's essential to maintain the proper oil level in your car's engine by referring to your owner's manual for the recommended oil level and follow it carefully during oil changes.

If you suspect you've added too much oil or one of those Quickie Lube style service centers added too much or dumped extra oil into your engine without draining the old oil out first, it's best to drain the excess to prevent any potential damage to your engine.

Related article: Two Simple Ways to Test Your Unused Motor Oil at Home

But What About a High-Performance Car?

Following your vehicle’s oil maintenance recommendations for type and amount is your best bet for properly maintaining your high-performance vehicle. However, what if you have a car with a high-performance engine and like to open her up on an open road occasionally (or more than occasionally) to see (and show) what she can do?

This raises some interesting questions about whether adding extra oil is warranted:

  • Are you protecting the engine by ensuring more oil than normal is getting to the engine during rough treatment?
  • Will more oil affect performance at lower and/or at higher RPMs?

The most accurate answer to this question is “It depends.”

High-performance―just like stock engines―are designed or modified to meet specific performance requirements. In other words, engines vary in how oil is monitored and delivered between models. Modifications within oil galleys can affect the flow as well. Therefore, what works for one engine could be disastrous for another.

In short, you really need to address this type of question on a case-by-case basis with dyno testing and a teardown of an engine after it has been subjected to higher RPMs and driving conditions.

However, a more general answer is possible as demonstrated in a recent The Motor Oil Geek YouTube channel episode where the host and co-host demonstrate the effects too little and too much oil has on an LS engine on their dyno, which is shown in the 2nd video―immediately below this one about LS engines:

What's So Special About the LS?


Dyno Test Results Using Too Much Oil on a High-Performance Engine

According to The Motor Oil Geek YouTube channel episode when it comes to the operation of your car’s engine, proper lubrication is defined by the four R’s:

  1. Right Oil
  2. Right Place
  3. Right Time
  4. Right Amount

With the first three “Rs” covered, here’s what they found performance-wise when too little and too much oil was added to the engine and put to high RPM running conditions.

How Much Oil is Too Much? Dyno Results!


For more articles related to car oil, here are a few for your consideration:

Timothy Boyer is an automotive reporter based in Cincinnati. Experienced with early car restorations, he regularly restores older vehicles with engine modifications for improved performance. Follow Tim on  “Zen and the Art of DIY Car Repair” website, the Zen Mechanic blog and on Twitter at @TimBoyerWrites  and Facebook for daily news and topics related to new and used cars and trucks.

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