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HKS ADD-II Engine Oil Additive 200ml for Mazda RX8 (Series 1 & 2, 2003-2012)

Organic molybdenum treatment that reduces friction and targets dry-start wear in the Renesis rotary. A considered addition to any RX8 oil service.

Mazda RX8 oil additive HKS ADD-II 200ml silver can with black cap

$45

This Mazda RX8 oil additive is a 200ml organic molybdenum treatment from HKS, designed to reduce internal friction and support wear protection during the dry-start phase of every cold start. The Renesis rotary builds oil pressure quickly, but that brief window before full pressure is where internal surfaces are most exposed. ADD-II bonds to those surfaces and stays active between oil changes.

Mazda RX8 Oil Additive Key Features

  • Organic molybdenum formula bonds to internal engine surfaces to reduce friction under normal operating loads.
  • The additive targets the dry-start window specifically, the brief period before oil pressure fully builds on every cold start.
  • 200ml single-service quantity makes it straightforward to plan alongside a routine oil change without measuring or splitting a larger bottle.
  • Suits all RX8 models from 2003 to 2012, covering both Series 1 and Series 2 without any variant-specific restrictions.
  • Finally, ADD-II is a complement, not a substitute, correct oil selection, a quality filter, regular level checks and any needed mechanical repairs all remain essential.

For RX8 enthusiasts, Josh pairs this RX8 oil additive with R-MAGIC Racing Energy Oil. He told Ryan to establish a solid baseline service first, because he was confident the difference would be clearly noticeable. Josh subsequently described the result as more than subtle. That is first-hand experience, not a quoted figure. The improvement shows up during warm-up and becomes most apparent as the engine climbs toward the redline.

For rotary enthusiasts who want to complete a thorough engine service with a quality Mazda RX8 oil additive in the mix, round it out with a GREDDY TRUST Oil Filter and a GREDDY TRUST Super Magnetic Oil Pan Sump Plug. The filter keeps the oil clean; the magnetic sump plug captures fine metallic particles between changes.

Together they give the Renesis the best possible lubrication baseline for ADD-II to work from. The full HKS treatment range is available on the HKS official website.

Additional information

RX8 Model

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SKU HK-OAD-S1S2 Categories , Types , Brand:

Related RX8 Upgrades

This engine oil additive is one of the best Mazda RX-8 upgrades you can make to your Series 1 (2003-2008) or Series 2 (2009-2012). Oil additive upgrades are among the top Aftermarket mods you can buy from HKS for owners who want better performance and reliability from their RX8. If you are looking for rx8 engine oil additive for sale in Brisbane (QLD), Sydney (NSW), Melbourne (VIC), Canberra (ACT), Adelaide (SA), Darwin (NT) or Perth (WA), you’ll find high-quality Japanese Engine upgrades at RX8 Upgrades.

Frequently Asked Questions

What does HKS ADD-II actually do for a rotary engine?

HKS ADD-II is an organic molybdenum oil treatment that bonds to internal engine surfaces to reduce friction under normal operating loads. It targets the dry-start phase specifically, the window before oil pressure fully builds after a cold start, which is a period of measurable wear stress for rotary internals like apex seals and rotor housings.

Does ADD-II replace my engine oil or oil filter?

No. HKS ADD-II complements a quality engine oil; it does not replace correct oil selection, a sound filter, regular oil-level checks, or mechanical repairs. It is added alongside a full oil change as an additional friction-reduction step, not as a substitute for any part of a proper service routine.

Will this suit both Series 1 and Series 2 RX8 models?

Yes. HKS ADD-II is compatible with all Series 1 (2003-2008) and Series 2 (2009-2012) RX8 models, covering both generations of the Renesis rotary engine.

How much ADD-II do I use per service, and how often?

Each 200ml bottle is sized as a single-service quantity, making it straightforward to plan alongside a full oil change. The defined volume removes any guesswork about how much to add each time you service.

When is the best time to introduce ADD-II into my service routine?

Our store owner Josh recommends establishing a clean baseline with a fresh oil change first before introducing ADD-II, so any improvement in engine feel is clearly attributable. Adding it as part of a routine oil service rather than mid-interval gives the formula the best environment to bond to engine surfaces.

What other service parts pair well with HKS ADD-II?

A GREDDY TRUST Oil Filter makes a natural companion for a complete service refresh, while a GREDDY TRUST Super Magnetic Oil Pan Sump Plug helps capture fine metallic particles between changes. Running all three together gives the lubrication system a thorough upgrade beyond a standard oil-only change.

Is HKS a reputable brand for this type of product?

HKS is a long-established Japanese performance brand with decades of development work focused on high-revving engines. ADD-II sits within a product range built with that same engineering focus, making it a considered choice for the free-revving Renesis rotary rather than a generic off-the-shelf additive.