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  • Writer's pictureRoger Maeda

How Well Did PTH Racing Oil Protect our Honda Race Engine?

Over the course of the 2018 season we took a in-depth look at PTH Racing Oil, thrashed it in our Honda Prelude Si racecar, and had Blackstone Laboratories analyze the oil to see how it stood up to high-rpm use on a racetrack. Once the season ended, powertrain wizard Robert Oliver tore the motor down so we could see what was happening inside. Now it's the moment of truth - Did PTH's Racing Oil live up to its claims of superior protection at a racer-friendly price?


Test Platform and Conditions

Once again, our test platform of choice is the StudioVRM Prelude, a 93 Honda Prelude Si powered by the non-VTEC H23A1 motor. In the first half of the 2018 season we installed a set of custom ground racing camshafts from Racer Brown Camshafts with Crower valve springs to match, added a pair of AEM adjustable cam gears, and gave it a new tune to push it to just shy of 180whp.

In order to ensure that we got consistent test results, we ran the car in exactly the same way as we had earlier in the year. All of our four race weekends took place at one of the two tracks at NJ Motorsports Park, and the same driver piloted the car at every event. We did raise the rev limiter again, so the engine spent most of its time between 4200 rpm and 7500 rpm in 3rd, 4th, and 5th gear.

As with before, there were no unexpected noises nor did the engine consume any oil. Oil pressure remained above 40 psi through even the hottest race sessions, and there was little to no oil in the PCV catch can after each session. So far, so good. How did the metal internals of the engine look after a full season of racing?


Checking the Head and Valvetrain

High-lift racing camshafts and stiff aftermarket valve springs exert a tremendous amount of pressure on the surfaces of the cylinder head. This can cause a lot of issues in modified Honda motors, which are usually built to run at high RPMs using extremely high lift cams.

Any wear would be clearly visible in the tops of the rockers and the surrounding surfaces of the head. Would there be any scratching, bluing, and flattening on these critical surfaces?

Fortunately, Robert found none of those characteristic wear marks when he disassembled the Prelude head. The top end of the motor looked just as shiny as it was before he had installed the new cams and valvetrain. The rockers showed no signs of flattening, while the head and cam caps had the same consistent color as the rest of the head.

From what we could tell, the robust additives package and inherent film strength of PTH 5w30 has done a fine job of protecting the delicate valvetrain of our race motor. On to the bottom end.


Cracking Open the Block

While the head has been removed and inspected countless times, the bottom end of this motor has never been disassembled. We didn't expect to see much wear on the hardened FRM-sleeved bores of the Honda H motor. But at the same time, we expected that regularly running the car 1000 rpm above its factory redline would have taken a toll on the OEM crank bearings.

To our surprise, the rod and main bearings showed no signs of scoring or accelerated wear. In fact, a close inspection of the old bearings showed that they were still within the factory spec of thicknesses and wear.

Here's a close-up of the rod bearings. They're a bit dirty but are in great shape otherwise:

And here are the crank main bearings. Keep in mind that these were the original, unmodified Honda bearings, manufactured and installed in the engine over 20 years ago.

Take a look at the piston skirts on these original H23A1 pistons:

After years of track use and the especially strenuous conditions we put the motor through last year, we would have expected the piston skirts to be worn totally smooth. Yet, the lathe marks from the factory process are still intact, all the way down to the bottom. Robert remarked that, with a bit of cleaning, these pistons look like they could go right back into the motor for another season of track use.

The Blackstone oil analysis was accurate. PTH Racing Oil really does have what it takes to protect race motors in the toughest of conditions.


Conclusions and Recommendations

After a full year of real-life testing and lab analysis, I think it's safe to say that PTH Racing Oil lives up to its claims of best in class stability and protection for racing engines. And frankly, I couldn't be happier.

As a privateer team with limited resources, we can't afford to do yearly rebuilds and replace internal engine parts on a regular basis. At the same time, we need to be able to run our engines 1000 rpm above the factory redline for hours at a time in order to be competitive in our class. PTH 5w30 proved that it could give us the protection and longevity we need to race a production based engine, regardless of its level of modification. The fact that it's cheaper than other well-known racing oils is just icing on the proverbial cake.

So yes. If you own a dedicated track car or race car, I would wholeheartedly recommend PTH Racing Oil. It offers a level of protection that is simply impossible to find in street car oils at a price that the average club racer can easily afford. At the very least, StudioVRM Racing Team will be using it as our go-to racing oil in the seasons to come.

See you at the track.


Disclosure Section:

StudioVRM, Roger Maeda, and Robert Oliver are not sponsored or supported by any oil companies, including PTH and Blackstone Laboratories. All of the products and services mentioned were purchased at full retail price out of Roger's own pocket. After seeing these results, this doesn't bother him at all. Paying a few hundred dollars for three cases of oil is nothing compared to the thousands of dollars it would cost to rebuild a race engine.


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