Archoil AR9100 Review – Does This Friction Modifier Work?

Most oil additives are easy to dismiss. They’re heavily marketed, vaguely defined, and rely on the fact that most buyers will never have a precise before-and-after measurement of anything. Archoil AR9100 is different — and not because it’s necessarily better chemistry than everything else on the shelf, but because it has a genuine, documented use case with a specific engine that’s genuinely difficult to fix any other way.

This review covers what AR9100 actually is, what it does chemically, where it earns its keep, and where it’s simply not worth the money.

What Archoil AR9100 Actually Is

AR9100 is a nanoborate friction modifier sold as an oil additive. You add it to your existing engine oil — typically at a ratio of around 5–10% of the total oil volume — and it’s supposed to reduce friction, lower operating temperatures, quiet noisy components, and extend engine life.

The “nano” prefix refers to the particle size of the boron compounds in the formula. Archoil claims these particles are small enough to penetrate the microscopic surface asperities of metal components and fill them in, creating a smoother, harder surface that reduces metal-to-metal contact.

It’s available in 473ml (16 fl oz) bottles, which is the standard treat dose for most engines. The product is made in the USA and sold internationally.

The Marketing Claims

Archoil’s marketing is heavy on testimonials and light on independent third-party validation — which is standard for the additive industry. The company claims AR9100 will:

Eliminate stiction in diesel injectors
Reduce engine noise and vibration
Lower oil temperatures
Improve fuel economy
Provide wear protection beyond what the base oil offers

Some of these are plausible. Some are the kind of generic claims you’ll find on virtually any additive bottle. The fuel economy claim, in particular, should be taken with significant scepticism — any effect is likely to be marginal and unmeasurable without laboratory conditions.

The Chemistry — Nanoborate Explained

Borate chemistry has genuine anti-friction credentials. Boron compounds have been used as solid lubricants in industrial applications for decades. The theoretical mechanism works like this: borate nanoparticles deposit on metal surfaces under heat and pressure, forming a low-friction boundary layer that reduces direct metal contact.

Unlike ZDDP (zinc dialkyldithiophosphate, found in products like STP Oil Treatment), boron compounds are not corrosive to catalytic converters or DPF systems in the concentrations used in AR9100. This matters particularly for diesel engines with diesel particulate filters, where phosphorus-heavy additives can cause problems over time.

The key question is whether the nanoborate particles in AR9100 actually behave as described under real-world engine conditions, or whether they’re simply flushed through the oil system without having meaningful contact time on metal surfaces. Independent tribological research on nanoborate additives does show genuine friction reduction in controlled tests — the mechanism is real. Whether a consumer-grade additive delivers this reliably is harder to verify.

The 6.0L and 6.7L Powerstroke Story

This is where AR9100’s reputation actually comes from — and it’s worth being precise about which engines benefit.

The Ford 6.0L Power Stroke (2003–2007) is the engine where AR9100 has the most documented real-world success. This engine has a known chronic problem: Hydraulic Electronic Unit Injectors (HEUIs) that develop stiction. Stiction is essentially the injector spool valve sticking due to a combination of varnish deposits and high-viscosity oil at cold temperatures. When this happens, the engine runs rough at startup, misfires until it reaches operating temperature, and can exhibit hesitation under load.

The stiction mechanism on the 6.0L responds well to AR9100 because the nanoborate chemistry reduces the surface friction on the spool valve, making it less likely to stick even when cold oil is viscous. Users across Powerstroke forums consistently report that rough cold starts and stumbling disappear after running AR9100 through an oil cycle. This isn’t marketing — it’s a forum consensus built over years of real use by actual diesel mechanics.

The Ford 6.7L Power Stroke (2011–present) is a different story. This is a Ford-designed engine (unlike the 6.0L, which was International/Navistar). It uses piezoelectric common-rail injectors rather than HEUIs, and it does not have the same stiction vulnerability. If your 6.7L is running correctly, AR9100 is unlikely to produce noticeable results. Some 6.7L owners report quieter operation and smoother running, but this is anecdotal and the 6.7L doesn’t have the documented mechanism that makes the 6.0L treatment so compelling.

The 7.3L Power Stroke (1994–2003) is similar to the 6.0L — it also uses HEUI injectors and benefits from AR9100 for the same reasons.

Where AR9100 Genuinely Helps

Ford 6.0L and 7.3L Power Stroke diesels with stiction. This is the clear use case. If your truck stumbles, misfires, or runs rough when cold and then clears up once it reaches operating temperature, stiction is the likely cause, and AR9100 has a reasonable track record of addressing it. It won’t fix physically damaged injectors, but for spool valve stiction caused by varnish and friction, the treatment makes chemical sense.

Hydraulic lifter noise on older petrol engines. Classic and high-mileage engines with hydraulic valve lifters that tick on cold start may benefit from a friction modifier. The borate coating on lifter components can reduce the metal-to-metal contact that causes the ticking. This is a less dramatic application than the diesel stiction case, but plausible.

Older engines with sliding contact valve trains. Pre-direct-injection, pre-VVT engines with flat-tappet camshafts or high-friction valve trains are reasonable candidates if the engine is experiencing friction-related noise or wear.

Where It’s Overkill

Modern petrol engines with OEM-spec oil. A BMW B48, a VAG 1.5 TSI, a Ford 1.0 EcoBoost — these engines are designed to run with specific low-viscosity synthetic oils that meet OEM specifications (BMW LL-04, VW 504/507, Ford WSS-M2C948-B). The additive packages in these oils are already carefully balanced for the engine’s materials, clearances, and catalytic converter system. Adding AR9100 does not improve on a properly formulated OEM-spec oil, and introduces a variable that the manufacturer never tested.

Any turbocharged petrol engine. Turbos rely on oil flowing rapidly through small passages to cool and lubricate the bearings. Any uncertainty about how an additive might interact with your base oil’s viscosity characteristics — particularly at high temperatures in the turbo centre section — is a reason to avoid it.

Engines under warranty. Adding any aftermarket additive to a warranted engine complicates any future claims. It’s not worth the risk.

Diesel engines with active DPF regeneration. While Archoil claims AR9100 is DPF-safe, it is not factory approved for use in engines that require specific low-SAPS oil specifications (such as ACEA C1 or C2). If your vehicle requires low-SAPS oil, stick to it.

Price and Availability

UK: Approximately £20–£25 for a 473ml bottle from Amazon UK or specialist diesel performance suppliers.
US: Approximately $22–$28 for the same 473ml bottle from Amazon US, Archoil’s own website, or Powerstroke-specific parts retailers.

One bottle treats a typical engine oil fill (5–6 litres), so the cost per oil change is meaningful but not outrageous if you have the specific problem it’s designed to address. For a 6.0L Powerstroke owner dealing with stiction, this is cheap compared to injector replacement.

Our Verdict

AR9100 is not a miracle in a bottle, but it’s also not a scam. It occupies a specific, narrow niche: Ford HEUI diesel engines with injector stiction, and it genuinely works there. The chemistry is sound, the mechanism is plausible, and the forum evidence for 6.0L and 7.3L Power Stroke trucks is credible enough to take seriously.

Outside that niche, the case weakens considerably. For a modern petrol car running the right OEM-spec oil, you do not need AR9100. Your oil is already more precisely formulated than any generic additive can improve upon. Save the £25.

If you own a 6.0L Power Stroke that stumbles until it warms up, AR9100 is worth a try before you spend hundreds on injector diagnostics. If you own anything else, spend the same money on a quality full synthetic that meets your vehicle’s OEM specification — the effect on long-term engine health will be far more measurable.

Verdict: 4/5 for its intended use case. 2/5 for general application.