Iridium vs Copper Spark Plugs: Life, Cost and Performance

The title of this article poses the familiar spark plug comparison — iridium against copper — and the honest place to start is with what this catalogue actually prints about the two sides of its spark plug range, because the catalogue's presentation is not what the question expects. The spark plugs range holds 28 detailed listings under NGK type codes. One group of codes carries an IX suffix, and another group sits under the DILFR, IFR and IL prefixes; the rest are the standard codes. This article uses the code groups as the catalogue presents them — setting out what the listings state, what they state identically across both groups, and what they do not state at all.

The two groups as listed

The IX-suffix group: BKR5EIX11 (Accord, Civic, Odyssey), BCPR6EIX (Avensis, Carina, Crown), BKR6EIX11 (Aristo, Progres, Windom), DCPR7EIX (Mito, Avanza, Punto), DCPR8EIX (Rumion, Starlet, Urban Cruiser) and BKR7EIX (Cruze, Beetle, California). The DILFR/IFR/IL group: DILFR5E11 (Aurion, Auris, Crown), DILFR6D11 (Aurion, Sienna, Harrier), IFR5T11 (Allion, Altezza, Aristo), ILTR5A13G (MPV, MX-5, Biante) and ILZKR7B11S (Crosstour, Pilot, Durango). The standard-code group includes BCP5ES-11 (Accent, Camry, Corolla), BKR5E11 (Camry, Corolla, Celica), BKR5ES11 (Accent, Atos, Getz), BKR6E (Avensis, Corolla, Yaris), BKR6E11 (Altezza, Camry, Corolla), BKR6EGP (Camry, Corolla, Harrier), BKR6EZ (Avanza, Carina, Corolla), BPR6ES (Corona, Crown, Hilux) and BP6ES (Carina, Corolla, Cressida). Each listing is titled with its applications and printed with cross references — FR8DP, IK16 and 90919-01265 against BKR5EIX11, for example.

What the listings state identically

Here is the fact that disciplines the whole comparison: the listings print one construction line across the range — "Nickel alloy, Copper core center electrode" — and they print it on the IX-suffix and DILFR/IFR/IL listings exactly as they print it on the standard codes. It appears on BCPR6EIX, on BKR5EIX11, on DILFR5E11's group listings, and on BCP5ES-11 and the other standard codes alike. The thread specification is printed per listing: M14 x 1.25 on BCP5ES-11, on BKR5EIX11 and on BKR5ES11, and M12 x 1.25 on ILZKR7B11S. A comparison that assigned different electrode constructions to the two groups would be contradicting the listings it claims to describe, and this site does not do that. As presented by the catalogue, the groups differ in their codes, their application lists and their cross-reference sets — the construction line they carry is the same line.

What the listings do not state

The catalogue prints no service-life figures for any plug code — no mileage, no interval, no comparative life claim between the groups. It prints no prices, so no cost comparison between the groups can be drawn from it. It prints no performance data — no output, efficiency or starting comparisons. Buyers arriving with a life-versus-cost question will find that this catalogue simply does not contain the axes of that comparison, and any article that supplied them would be inventing them. What can be compared from the listings is set out in the next section; it is less dramatic than a life-and-cost verdict, and it has the advantage of being true to the source.

What can be compared from the listings

Applications. The groups serve different, overlapping vehicle sets. The standard codes carry the long Toyota tail — Corolla under seven standard listings — while the IX and DILFR/IFR/IL groups carry applications such as Pilot, Durango, MX-5 and Punto alongside Toyota and Lexus-platform models. A distributor maps coverage from the application lists, which are printed in full on the iridium spark plugs and copper spark plugs pages.

Cross references. Each listing prints its set — three numbers against BKR5EIX11 (FR8DP, IK16, 90919-01265), three against ILZKR7B11S (YR6SII33, 3461, CCH9407). The sets are the working connection between a code and the other number systems a workshop stocks.

The code itself. The code is the stock unit and the ordering unit. The catalogue organises 28 listings by code, and a mixed order across both groups is written as codes and quantities.

Choosing, on the catalogue's evidence

On the evidence the listings provide, the choice between the groups is not a judgement the buyer makes about plug technology; it is a matching outcome. The code on the plug being replaced identifies the listing; the buyer checks the application lists against the vehicle; the cross references connect it to other stock systems. Where a vehicle appears under codes in both groups — the Crown appears under BPR6ES, BCPR6EIX and DILFR5E11 in different listings — the catalogue does not rank the listings; identify the listing from the replaced plug's code, or send the vehicle and engine details with your enquiry. That is less satisfying than a universal verdict, and it is how the range is actually organised.

The application overlap, concretely

The overlap between the groups is easiest to see on one model. The Crown appears under BPR6ES (Corona, Crown, Hilux) among the standard codes, under BCPR6EIX (Avensis, Carina, Crown) in the IX group, and under DILFR5E11 (Aurion, Auris, Crown) in the third group — three listings, three codes, one model name, and no ranking among them anywhere in the catalogue. The Corolla runs the other way: seven standard-code listings name it (BCP5ES-11, BKR5E11, BKR6E, BKR6E11, BKR6EGP, BKR6EZ and BP6ES) and no IX or DILFR/IFR/IL listing does. A distributor reading the range learns coverage from these lists — which models the catalogue serves under which codes — and that, rather than a technology verdict, is the comparison the listings support.

Ordering facts for this family

• Minimum order quantity: Not published for this line in the catalogue details; ask for it in your enquiry.
• Samples: Free samples are offered.
• Delivery: No plug listing prints its own delivery window; the company FAQ gives a general figure of 30–40 days.

Frequently asked questions

Which lasts longer, an IX-code plug or a standard code?

The catalogue prints no service-life figures for any of its 28 plug listings, so no life comparison can be drawn from it. The listings give codes, applications, cross references and the shared construction line.

Do the IX and DILFR/IFR/IL listings use a different construction?

As listed, no: the construction line "Nickel alloy, Copper core center electrode" is printed on those listings just as on the standard codes. The thread is printed per listing — M14 x 1.25 on BCP5ES-11, BKR5EIX11 and BKR5ES11, M12 x 1.25 on ILZKR7B11S.

How do I choose between the groups for a vehicle I stock?

By the code on the plug being replaced — read it against the application lists printed with each code. Where a model appears in both groups, send the vehicle and engine details with your enquiry.