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Every Grand Marquis from 1992 through the 2011 final model year runs Ford’s 4.6L modular V8, so the fitment question is simple — the choice is really about metal (copper, platinum, or iridium) and how long you want between changes. Here are seven confirmed-fit options across that spectrum, from the factory-style copper plug to long-life iridium.
| # | Product | Price | Where to buy |
|---|---|---|---|
| 1 | NGK V-Power TR55 | $22.99 (set of 8) | Amazon · eBay |
| 2 | NGK G-Power Platinum TR55GP | $8.49 each | Amazon · eBay |
| 3 | Autolite Double Platinum APP104 | $6.55–$7.49 each | Amazon · eBay |
| 4 | Champion Iridium RS12WYPB4 | $11–$15 each | Amazon · eBay |
| 5 | Champion Copper Plus CJ8 | $31.92 (set of 8) | Amazon · eBay |
| 6 | Denso Platinum TT / Iridium TT 4713 | $8.80–$14.99 each | Amazon |
| 7 | Motorcraft SP479 Platinum | ~$6 each (10-pack $59.89) | Amazon · eBay |
The picks, in detail
NGK V-Power TR55
A copper-core V-groove plug sold as an 8-piece set specifically matched to the Grand Marquis 4.6L.
- Copper-core center electrode
- V-groove design for improved ignitability
- Cheapest set here at roughly $2.87/plug
- Proven, high-volume replacement plug
- Shortest service life of the options here (copper wears faster than platinum/iridium)
NGK G-Power Platinum TR55GP
A single-platinum-tip step up from the V-Power line, listed by NGK for 1992–2008 Grand Marquis models.
- Single-platinum center electrode tip
- 14mm tapered-seat thread
- Longer service life than the copper V-Power
- Reasonably priced platinum option
- Not as long-lived as iridium
Autolite Double Platinum APP104
Double-platinum-tipped plug (both center and ground electrode) rated for a longer service interval than single-platinum designs.
- Platinum-to-platinum firing
- Double-platinum construction for reduced misfires
- Confirmed retail pricing across multiple major retailers
- Mid-pack cost for a double-platinum plug
Champion Iridium RS12WYPB4
Fine-wire iridium plug sold as an 8-pack specifically listed for the Grand Marquis 4.6L (1992–2011).
- Iridium center electrode
- Fine-wire design for consistent spark energy
- Up to 25% longer life than platinum per Champion’s spec
- Covers the full model-year range in one part
- Priciest per-plug option on this list
Champion Copper Plus CJ8
A budget copper-core plug, the direct competitor to the NGK V-Power at a similar price point.
- Copper-core center electrode
- Ultraseal-coated shell
- Lowest cost per plug
- Rated for up to 20,000 miles
- Shortest change interval of any option here
Denso Platinum TT / Iridium TT 4713
Denso’s twin-tip design, sold in multiple part numbers matched to the Grand Marquis 4.6L across different model years.
- Twin-tip platinum or iridium electrode (part-number dependent)
- 0.4mm fine-wire tip on the iridium variant
- Rated for well beyond 100,000 miles on the iridium TT variant
- Multiple part numbers for different years — confirm the one matched to your model year
Motorcraft SP479 Platinum
Ford’s own-brand plug — the same part that left the factory on many Panther-platform Fords and Mercurys, including the Grand Marquis.
- Platinum tip
- 60,000–100,000 mile rated service interval
- Factory-match part from the vehicle’s own manufacturer
- Reliable bulk pricing in 8- or 10-packs
- Sold mostly in bulk packs, less convenient if you only need to replace a few plugs
Buying tips
- All Grand Marquis model years (1992–2011) share the 4.6L modular V8, so fitment isn’t the issue here — pick based on how long you want between changes.
- Copper (NGK V-Power, Champion Copper Plus) is cheapest but shortest-lived; iridium (Champion Iridium, Denso Iridium TT) costs more up front but goes the longest between changes.
- Motorcraft SP479 is the factory-equivalent part if you want to match exactly what Ford originally installed.
As an Amazon Associate and eBay Partner, toptenpick.com earns from qualifying purchases. Prices and availability are subject to change.