Project EP3 Civic Si: Can an Oil Change Affect Horsepower?

by Mike Kojima


A lot of people have asked this question before and the jury has been out on whether this is something that is true or not. We have attempted to test to see whether certain brands of high-quality oil have a gain in power over others before with mixed results. Our dyno tests have always been inconclusive with the differences being too small to be considered or perhaps caused by variables such as differences in viscosity or sump level.

One of the things here is all of our cars in our fleet all run with some sort of premium performance synthetic oil in the pan.  We think that perhaps we have proven that when all else is equal there isn't much power difference in power output between one brand of premium synthetic oil to another.  

Believe it or not, we have never dyno tested the difference between regular dino oil and a premium synthetic on our dyno before, so we decided it was time to see!


Our test subject is the shop beater, Project EP3 Si. Its wheezy K20A3 engine is the subject of contempt around here since the car has the questionable honor of the being the slowest car of the MotoIQ fleet.  

Fortunately, it also gets the best mileage and it holds a lot of gear, so it gets driven a lot running cameras and stuff to the track and back. The EP3's engine also gets neglected because, well, it's slow. Because of this, it gets fed regular dino oil bought in the AutoZone sales bin that also goes in the lawn mower and generator.  We at least got the right gas saving 5W20 viscosity for it most of the time.   


To start our test, we strapped Project EP3 to our stingy Superflow dyno and laid down a very surprising 120 whp and 114 lb/ft of torque.  

What was cool is that the neutered by the factory K20A3 engine made its peak torque at 2400 rpm and had a nice flat torque curve all the way to the 6800 rpm redline. Everyone loves to hate on the poor A3 as the retarded step-brother of the A2, but it does have its merits.


To make sure we had as close to equal oil levels for the before and after test, we checked the oil level right after our dyno runs.

We have found that the oil level and associated windage losses can make a few hp difference on the dyno, and since our anticipated power gains will be small, we wanted to make sure that this would not be a factor. 


To be honest, no one around here could remember the last time we changed the oil in the EP3. However, the oil on the dipstick didn't seem that bad.

It could be that the thin 5W20 that is the recommended factory fill burns faster, and we would occasionally have to add a quart which kept the oil on the fresh side!


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Friday, June 30, 2017 2:14 AM
Some time ago we switched Project Hoondy over to Neo Synthetic Oil in the engine sump and differential housing. 0W-30 synthetic in the engine and 75W-90RHD in the diff. Amazingly, even though we were running good synthetic oil previously, we picked up a repeatable power gain as confirmed by DashCommand.

Now, a lot of that was probably down to being at lower viscosity. The previous oil was 5W-30 for the engine and 75W-140 for the diff. I still have to give Neo Synthetics credit though, because their lower-viscosity oil lasts dramatically longer than higher-viscosity Penzoil Ultra. 20,000 miles or 1 year, whichever comes first. And that's before adding the super-saturated calcium petroleum sulfonate solution.

There is *definitely* performance to be had through use of the most modern of lubrication technology. For enthusiasts it can be worth playing around with, especially when the added cost is usually offset by a significantly increased service interval.

After long-term thrashing, we've been blown away by the Neo products. Their most impressive feat was smoothing out our CuscoRS 1.5-way differential. We thought we had it pretty well tamed before since we'd applied WPC treatment, but after the swap to the Neo RHD it became a total pussycat in comparison. Granted, we combined the Neo gear oil with plenty of Redline limited slip additive as well as Oil Extreme Concentrate.

Mike, do you have any experience with Neo Synthetic oils? They're just down in Signal Hill, near Long Beach. The boys at Mazdatrix are like *right* around the corner from them. If you've never had the chance to chat you guys at MotoIQ should check them out!
Friday, June 30, 2017 9:44 AM
RP has superior lubricity from everything I've read but on my B13 VVL setup it would fly through the PCV valve so I switched to German Castrol 0-30. One time while using RP I ran it almost to low on just a test n' tune at the local drag strip. Luckily I caught it. This was a perfectly healthy motor.

Also from what i read the EP3 only takes 5w-20 so Honda could qualify it as aLEV. Many dealerships switched to 5w-30 and I did as well because as the K-series motor has a similar PCV setup that will consume oil between change intervals especially if winding it out a lot. Swapping to 5w-30 limited consumption between oil changes.
Friday, June 30, 2017 9:45 AM
BTW nice job, interesting aricle.
Friday, June 30, 2017 11:08 AM
This is a great article. Thanks guys!

No negative side effect? I might question that. I picked up standard oil at Napa for $0.99/qt last weekend during a sale. HPS seems to be about in the $8/qt range.
So price would be the only negative.
Obviously, oil price is not a factor when you are buying oil for your expensive engine. I was buying the cheap stuff for my beater...

Fun article to read though. Thanks again!
Friday, June 30, 2017 12:55 PM
It'd be interesting to see this test again with 5,000mi of wear on the racing oil, then go back to cheap oil. Then send the used oil to Blackstone for analysis to see what happened to the oil and how that might affect power.

I would bet with new oil under ideal conditions there's probably a lot less difference, and I'd bet the high-end synthetic shows less viscosity breakdown and still has more of its additive package left at the end of the interval.
Friday, June 30, 2017 9:15 PM
I'd like to see old synthetic dyno'd then do an oil change with the same synthetic. I wonder if you'd see the same gains?
My bimmer always feels more smooth and possibly more peppy after a fresh oil change.
Mike Kojima
Mike Kojimalink
Friday, June 30, 2017 9:55 PM
Engineered, We have dynoed old synthetic vs new and different brands vs other brands of synthetic and have not seen any definitive gains in power before.
Friday, June 30, 2017 10:40 PM
@Mike, thanks for the reply. Nice to know.
I wonder if the improvements I've seen are mostly due to a clean filter providing less resistance, and on my E46 the oil separator isn't great so I wouldn't be surprised if my oil is excessively thinned out with vapors from blowby.
Sunday, July 02, 2017 4:23 AM
I had run RP in my Supra since day one. I had dynoed the car countless times and knew exactly what it made. Was very consistent. One day as I was on the dyno, an ENEOS oil rep came in and offered me some of their new oil. He said he guaranteed it would make significant power. I was sceptical. Changed out the RP and ran the ENEOS and was shocked to make an additional 8 RWHP

So yea, oil can make a difference.
Wednesday, July 05, 2017 11:56 PM
Interesting RRocket.
Curious as to what viscosity you used and was the ENEOS different?
Also what was the product name of the RP oil you were using and ENEOS oil he got you to switch to? Would like to pick out any other differences between the two by identifying the exact product and looking them up.
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