It's been four months since we started our long-term test of PTH Racing Oil, and we've been busy putting this new racing oil through its paces. As we use up the last few bottles in our first case of PTH 5w30, I thought I'd do a quick report on all of the work that we've been doing to see if PTH Racing Oil really is a top tier racing oil.
The Testbed
The testbed for this long-term test is the recently re-liveried #7 StudioVRM Prelude, a 1993 Honda Prelude Si prepared for SCCA Improved Touring S. The engine is a Honda H23A1 non-VTEC, a stout, undersquare engine that came from the factory producing 160hp and 156 lb-ft of torque at the crank. Rather fortuitously, this motor is ideal for this type of testing.
Being fairly simple, the H23A1 is pretty representative of popular production engines of the 80s, 90s, and early 2000's. No variable cam lift, no direct injection, no electronic throttle, and no unusual behaviors that could help or hinder the performance of the engine's oil.
The engine itself is close to stock as the Improved Touring rules prohibit significant modifications to engine internals. Even more so than usual in this case, as Robert Oliver, all-around powertrain wizard and my go-to engine builder, insisted that I use dealer-sourced OEM parts wherever possible. So that's what it has. The valvetrain, bearings, oiling system, electronics... even the water pump and timing belt are from American Honda.
Although the rules allow for it, the car is not equipped with an oil cooler or an Accusump. For measurement purposes, I've added a fast-acting Autometer mechanical oil pressure gauge and a PCV catch can to prevent blow-by from being sucked into the intake. Aside from that, an AEM intake, Hytech header, custom exhaust, and a Hondata S300 ECU are the only other power adding mods on this car.
If you are like one of the many people out there who track or race a stock or relatively unmodified production car engine, the results of this test should be pretty applicable to you.
Preparing for Testing
As the engine had run two race seasons since its last rebuild, Robert meticulously inspected the internals in the 2017 off-season. He confirmed that both the head and block were in good shape and installed a new timing belt, tensioner, and water pump for good measure. Aside from a bit of nominal bearing wear from hard racing use there was little to worry about with the motor itself.
Second order of business was getting the old oil out and getting the crank case full of PTH Racing oil. So as part of pre-season prep, the Prelude's crankcase was completely drained of PennGrade1 and refilled with 4.5 quarts of PTH 5w30. The oil filter of choice is Denso's FTF, a reliable and affordable OE replacement filter.
Of course, it's nearly impossible to get all of the old oil out of a production car engine in one oil change. So this first batch of new oil was only used to protect the motor while it was driven around the garage and between shops while the car was prepared, aligned, and set up for the 2018 race season. Once the car was in good mechanical order, I changed the oil again with another 4.5 quarts of PTH 5w30 and a new Denso oil filter. Wasteful? Yes. Call it a sacrifice in the name of science.
Dyno Tuning Time
The first test for the PTH 5w30 would be a dyno re-tuning session at Evans Tuning. The map on the car's Hondata S300 ECU had become corrupted over the winter, so Jeff Evans had to re-tune the car from some older code.
Jeff ran the car on the dyno for a full hour, adjusting it, revving it, and performing a number of full-throttle runs on his DynaPack until the car was running to his liking. The motor accepted this rude awakening from its off-season slumber without a single issue. Oil pressure remained a healthy 40 to 80 psi with no increase in valvetrain noise. As expected, the catch can remained empty.
The power numbers? A stout 157 hp and 162 lbs-ft of torque at the wheels. So with the H23 now idling happily and a successful first test completed, it was off to the racetrack.
On-Track Testing - By Racing
A few days after the dyno tuning session, we towed the Prelude to the Lightning circuit of NJ Motorsports Park for two days of on-track shakedown. Lightning is a fast, flowing 1.9 mile road course with long straights and a banked high-speed 180 degree turn affectionately known as "the Lightbulb", Lightning provides a good workout for engines while rewarding drivers who can conserve the most momentum at racing speeds.
With this being the third season for the Prelude in its current trim, there was little to do in terms of mid-session adjustments. So we maximized our track time and ran every lap of every session. This meant a little under two and a half hours spent between 4200 and 7000 rpm, mostly under full throttle conditions in 3rd, 4th, and 5th gear. It's fairly hard work for a production based motor.
As expected, there were no unusual noises and no oil consumption throughout the whole weekend. Oil pressure never dropped below 40 psi, even as the engine temperatures climbed throughout each session.
What was unexpected was that the PCV catch can remained empty through the weekend. We usually expect to see 1/4 of a quart of engine oil in the catch can after every hour of running on Lightning. This time there was no oil at all. It was a welcome surprise - with no Accusump and only the stock baffles in the OEM Honda oil pan, we can't afford to lose any oil from the crankcase.
A badly flat spotted tyre cut the second day of the weekend short. Still, the car and the oil clocked up the track miles as if it was just another day in the office. With plenty of time logged on the Hobbs meter, we loaded up the car and headed home.
At this point, we would normally call time on the engine oil and change it along with other worn-out fluids and consumables. But this wasn't a normal race weekend. It's a stress test. So against better judgement, we kept the same oil and the same filter and ran it in the SCCA Lightning Challenge races a month later.
One decent qualifying, one strong qualifying race, and one race-cancelling downpour later, we came away happy with an award for 1st in class and 4.5 quarts of well-used PTH Racing Oil sloshing around in the heart of the Prelude's H23A1. Now to see what sort of damage that all that hard use had done.
Used Oil Analysis
The next day I pulled the oil drain plug and relieved the Prelude of its heavily abused motor oil. While it was draining, I took a small sample and sent it off to Blackstone Labs for a Used Oil Analysis.
Here's what they sent back:
For comparison purposes, here's the virgin oil analysis that Blackstone did on a sample from the same batch.
Blackstone didn't have much data on road raced H23A1s, so I consulted my engine builder as well as a few Honda racers for their opinion on the metal content that appeared in the report. The general consensus was that this level of bearing wear would be expected from a regular oil change in a track driven H series motor. However SCCA racers change their oil after every race weekend (usually 2 hours or less for a sprint race weekend), while this oil was thrashed on for nearly 3 times as long. While I won't say that the oil protects the engine 3 times as well, it does indicate that PTH 5w30 is doing an above-average job of protecting the engine's internals.
Surprisingly, the on-track abuse and extra-long oil change interval didn't have much an effect on the oil itself. SUS Viscosity and cSt viscosity remained well within the acceptable range, and the Flash point remained a very high 415 degrees. The PTH 5w30 remained chock full of anti-wear additives with the Phosphorus and Zinc numbers barely changing from the new oil analysis. A still-high Total Base Number of 5.7 indicated that there was still lots of life left in the oil.
Although Blackstone recommended that I go back to more sensible oil change intervals, the numbers indicate that I could have run the car even longer on the same oil. That is pretty impressive, to say the least.
Results so Far
Shortly after the Used Oil Analysis, we towed the car back to Robert's garage. Once there, he removed the camshafts and I did a visual inspection of the heads. As expected, there was no additional wear on the cams, the rockers, or the caps. All mating surfaces looked shiny and unblemished, with no scratches or bluing from heat. So far so good. Between the results of the Used Oil Analysis and the condition of the valvetrain, it looks like PTH 5w30 is doing a very good job of protecting the fast-moving metal parts within the motor.
From the driver's seat, it's very difficult to tell if the PTH Racing Oil is extracting more power from the engine compared to other high performance oils. I did notice that the car didn't seem to lose as much power over the course of a race weekend compared to when it was on semi-synthetic PennGrade1.
Normally after 2 hours of hard racing, the motor would start to feel slightly sluggish - The revs would be a little slower to rise, and when blipping the throttle under downshifts you could tell that the engine just didn't seem to want to turn as freely. Not so in this case. Even after 5+ hours of time, the motor responded to quick jabs of the throttle just like it did the day after the oil change.
As I understand it, this is the difference between a semi-synthetic base stock and a "pure" synthetic Group IV or Group V base stock. Many petroleum based "dino" oils become more viscous with heat and shear. So over time the engine internals have to fight more and more against internal friction caused by the "thicker" fluid and has a hard time spinning as freely as they could. Most Group IV and Group V synthetic motor oils don't exhibit this property, with many of them becoming thinner over time.
Of course, you could change the oil more often. But I do like the idea that I could potentially run my engine oil through a 6, 12, or even 24 hour endurance race and not have to worry about protection or power loss. Based on my experience so far, PTH 5w30 seems to be an oil that could do just that.
Coming Up
Now that we've seen what PTH Racing Oil can do in a well-maintained stock motor, it's time to find out what it will do for a more modified engine. In preparation for this test, Robert is working with Racer Brown Camshafts to have a set of custom racing cams ground for the StudioVRM Prelude. The hope is that it will be ready and installed prior to the Summer Thunder weekend in early August.
How will this promising new oil stand up to the stresses and strains from aggressive high-lift cams, faster moving valvetrain, and a higher redline? The answers are coming in just a few short weeks.
In the meantime, I'll see you at the track.
Disclosure section:
StudioVRM is not sponsored or supported by any oil companies including PTH. Or by any dyno tuning companies including Evans Tuning. Or by any oil analysis companies like Blackstone Labs. Basically everything mentioned here was paid for out of Roger's own pocket. Except that oil drain pan. I nicked that from a friend.
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