Which Spark plugs and when?

[teK--]

Does anyone know for sure which plugs to use and how often to replace them?

In the Owner's Handbook it states that 2.5i non turbo are NGK PFR5B-11 (double platinum) in Europe, and Champion RC10YC4 (copper) for other models.

Presumably we fit into the latter category and are fitted with the Champion copper plugs?

It's confusing because in the Warranty & Service handbook it states "Spark Plugs (Turbo 50,000Kms, 2001-On Turbo, 6 Cyl & 2.5 DOHC 100,000Kms)" Then it ticks the sparkplugs as being needed at intervals 2,3 & 4 (25/50/100Kms respectively). So which interval is for which engine? The 2.5i (SOHC) which is what we have, isn't even mentioned!

Also has anyone changed these plugs themselves and can give an idea of DIY difficulty? Thanks

EDIT: The other confusing thing is that the LegacyGT (north American) owners who have a 2.5i non-turbo allude to the fact that they have platinum plugs as stock, that last 60,000MILES (100,000Kms). Going by our owner's handbook, only the European models get the platinum???

[teK--]

Come on has no one ever replaced the spark plugs in their 2.5i?

[TristosMaximus]

It appears not!!!! Lol

[sheppo9]

What year is yours?
They changed to Platinum's sometime in the 06 model's.

You can put Platinum's in, they last 100k, or change the coppers over every 25k.
Just depends if you could be bothered pulling all the crap out to change the plugs - I couldn't be bothered, and put in Iridiums.

[teK--]

Thanks Sheppo, I have an MY04.

Since I am so nice and all, I did lots of reading and can advise you all of the following options for the 2.5i:

1. (basic) BKR5E-11 - NGK Nickel Alloy (AUDM Stock Fitment), NGK recommend that they last 20-40,000Kms. Subaru's schedule recommends they be replaced every 25,000KMS. Approx $4.00 each, widely available.

2. (better) PFR5B-11 - NGK Laser Platinum (EUDM, JDM, USDM Stock Fitment). Both Subaru and NGK recommend that they last 100,000Kms. Repco quoted $29.00 each, special order.

3. (better) BKR5EIX-11 - NGK Iridium IX. NGK recommend that they last 60,000Kms. No recommendation from Subaru as these are an aftermarket option. Buy these from http://www.performancelub.com/NGK%20pricelist.htm for $14.00 each + $11.00 shipping or pay much more at a retail shop.

The use of either Iridium or Platinum is intended to give a stronger spark than nickel alloy due to the ability to manufacture a much smaller tip on the plug, however my reading on the properties of iridium is that it is more resistant than platinum to heat degradation. I conclude that at a later stage of service life (up to the maximum of Iridium at 60,000Kms, the spark should be more consistent instead of dropping off in performance.

If a brand new nickel alloy plug and a brand new iridium or platinum plug were compared there is probably no discernible difference in engine power output, but I am more concerned with durability. The platinums last longer and cost disproportionately more than the iridiums, but it's good practice to check the plugs at least semi-regularly to know the health of the engine rather than leave them in there for 100,000Kms which for some people could be 5 or more years!

I will be using the Iridiums and changing them at 50,000-60,000Kms.

Changing the plug is not that much trouble at all on the 2.5is; it should not be more than bout 30mins or 60mins if going at a leisurely pace. Full thread here:

http://www.legacygt.com/forums/showthread.php?p=2564978

Mods: Perhaps sticky this post?

[Ric]

...
Mods: Perhaps sticky this post?

I didn't notice this originally. Someone just reported it to recommend it be stickied. I've just mpoved the post to the " Reference material & Walkthroughs" forum so everyone can find it.

[mihai]

3. (better) BKR5EIX-11 - NGK Iridium IX. NGK recommend that they last 60,000Kms. No recommendation from Subaru as these are an aftermarket option. Buy these from http://www.performancelub.com/NGK%20pricelist.htm for $14.00 each + $11.00 shipping or pay much more at a retail shop.

You can buy these from Repco also, they are about $20 each however you get 20% off if you are an RACV member.