We get these questions a lot. What oil should I use in my 2017 Honda Civic SI? What is the recommended oil for my 2018 Civic Hatchback Sport? What oil and filter should I run in my 10th gen? What oil do you guys recommend for the W1 Turbocharger upgrade?

The above and many more variations of this question are easily one of the most talked and searched about topics in the forums and Facebook page groups. Countless enthusiasts new and old are searching the web, sending us an email, or asking a friend all in an attempt to answer the holy grail question; What oil should I run in my 2016+ turbo Honda Civic?

If you are subscribed to our YouTube Channel then you would have seen our oil change video. In it, we give our recommendation on weight and type. We said in the video we would dig into oil a bit more in a future blog. Well, today is the day and this is that blog.

“First a disclaimer; this is not intended to be the end-all-be-all blog of everything oil. There are scientists and companies whose sole purpose is to create and produce engine oils. We are not that. Our knowledge comes from years of developing parts for the 10th gen Civic platform, countless hours of R&D, track time, previous experience, engine oil analysis, consulting with various oil brands, partner companies, and race teams. The info that follows is the tried and true formula for oil selection for the CivicX platform as we see fit.”

Some framework. Both the L15 and the K20 engine variations both call for a full synthetic 0W-20 engine oil from the factory. 0 being the engine oil weight at freezing (0 degrees F) and the 20 being the viscosity at operating temperature (212 degrees F).

Viscosity (aka what we call oil weight) is a measure of the fluid’s resistance to deformation aka a given rate or simply put flow.

Viscosity is a resistance to flow, think syrup versus water

The reason you see nearly every car manufacture using thinner and thinner engine oil (less viscous) is because of the push to more stringent emissions. Thinner oil equals less friction/liquid to move equals more efficiency and better mpg, generally. With things like CARB and the EPA at the forefront, a great deal of focus is put on emissions over things like horsepower and torque.

On your stock to lightly modified turbo Honda the OEM 0W-20 is perfectly suitable. There is no reason to go to a thicker oil. In fact, going to a thicker oil can actually lead to some less desired effects like lower MPG and higher engine loads with no upside. It’s important to realize that Honda engineers spent years designing these engines to work around a certain set of parts for a certain period of time with this certain type of engine oil. It’s unlikely the average enthusiast can outdo years of research and development.

In the video, we outlined 3 scenarios when one should consider bumping up to a 5W-30 oil over 0W-20. We’ll expand on those reasons below.

Some of the best power to be had with the 10th gen, corn juice. aka Ethanol

1) RUNNING AN ETHANOL-BLENDED FUEL

As a performance enthusiast, we really love the benefits of ethanol mixed fuel. On our 10th generation Civics it’s not uncommon to see a 25-45whp gain just by adding an ethanol mixture into our gasoline. The thing about ethanol is that we require more of it to make the power. On average about 20% more fuel supply is needed to meet our air-fuel ratio targets. We have to run richer air-fuel mixtures which in turn means we are getting more fuel into the engine oil as a by-product of this setup.

This added fuel will break down the chemicals and additives in our engine oil and thus can make the fuel thin out sooner. Thinning out the engine oil leads to decreased wear protection and can be harmful to our engine. It is for this reason that we suggest a bump up in one viscosity grade to help combat this increased wear.

Another key reason is that ethanol-based fuels by their very nature absorb moisture. When your fuel is bringing in moisture it brings moisture into the crankcase. This can lead to excessive corrosion of critical engine components. By bumping up one viscosity grade we can help offset that a bit. It’s also a good idea to consider shorter oil change intervals with ethanol-blended fuel.

An increase of over 50% will warrant a change in oil thickness

2) ENGINE POWER INCREASES BY 50% OR GREATER

With added power also means added heat and pressure. It is heat that is the great equalizer of all and the one thing we try to combat in every performance situation. Since we are making more horsepower and torque we are generating more heat and more pressure. The added heat means the engine oil can get warmer and thin out quicker and the added pressure from the bigger burns in our cylinders equates to more pressure on our connecting rods and crankshaft. This means there is more pressure on the oil that is in between them. The oil’s job is to create a fluid barrier between all the rotating parts inside our engine. If the pressure gets too great the oil is forced out of those tight spaces and that can lead to metal on metal contact. When this happens it’s bye-bye engine. We help combat this by bumping up our oil weight.

3) WHEN OPERATING THE ENGINE IN A HIGH HEAT/HIGH LOAD ENVIRONMENT

aka racing

The last reason to consider different oil weight ties in pretty close to the others we mentioned above. When we are in a racing environment a couple of things are happening. We are generating a lot of heat and pressure. We are putting the car in a high-stress state for extended periods of time, like 20-40 minutes of wide open throttle (WOT). Another big one that people often don’t consider is the fact that when racing we also tend to be operating the car in a dirtier environment.

Have you ever been to a race track in California? Basically at any of them, if you go off or miss a turn then you are 99% likely to end up in an area with a lot of sand and dirt. That sand and dirt gets everywhere, and I mean everywhere, including your engine oil. We use a thicker weight oil to not only help with the heat but to also help suspend some of those dirty particles in the oil as opposed to them getting embedded in our bearings.

So what kind of oil should you use in your CivicX? Hopefully, with this information, you now have a good idea. Everyone’s situation and driving style is different. As always, it’s up to you to keep up with maintenance make those regular oil changes with the right oil.

I hope you found this useful and if you want to keep the conversation going drop a comment below.

-Vincent

The Great Oil Debate CivicX