Spark Plugs: NGK or Denso?

[slo town]

I read that someone changed their factory plugs on a Honda V6 and one side had Denso plugs and the other side had NGK plugs.

That tells me the heads are fully prepped (valves adjusted and spark plugs installed) before the heads get married to the block.

Scott

 

[Chris142]

I read that someone changed their factory plugs on a Honda V6 and one side had Denso plugs and the other side had NGK plugs.

the toyota fj was built like that

 

[zzyzzx]

Is there a sticker under the hood which states what spark plug to use?
Have you pulled one of the existing plugs to see exactly what it is?

 

[Kantaro]

My friend owns an independent Honda/Acura repair facility and he sees this all the time with the V6 Honda engines right from the factory.

So odd. BMW FSM makes a big stink about not mixing spark plug brands. I guess in a factory they have complete control over what goes in

 

[John105]

My friend owns an independent Honda/Acura repair facility and he sees this all the time with the V6 Honda engines right from the factory.

On my car the 3UZ-FE a sign that the dealer worked on the vehicle is 7 plugs are one kind and 1 is different by the dipstick. Dealers routinely avoid the plug near the dipstick or so urban legend goes

 

[John105]

So odd. BMW FSM makes a big stink about not mixing spark plug brands. I guess in a factory they have complete control over what goes in

I’d be curious if true because watching a Toyota Highlander YouTube rear bank is more difficult may be a case where dealer only did one bank of a transverse V6. For the factory do do things like that seems less likely

 

[slacktide_bitog]

On my car the 3UZ-FE a sign that the dealer worked on the vehicle is 7 plugs are one kind and 1 is different by the dipstick. Dealers routinely avoid the plug near the dipstick or so urban legend goes

I've heard of mechanics doing that on the old Aerostars too

 

[Craig in Canada]

OP - just be very persnickety when torquing those down, and heed the factory-updated torque specs. These engines are seeing lots of cases of plugs backing out and trashing the threads.

New spec is 20 ft-lb WITH anti-seize, which is a lot tighter than the original spec I've seen around of 13 ft-lb (sometimes wet sometimes dry).

The picture below was obtained online, and depicts the online and PDF service manuals floating about on the left which contain the original torque spec, and a printout from this person's local Honda dealer REVISED on the paper on the right.

 

[Number_35]

I read that someone changed their factory plugs on a Honda V6 and one side had Denso plugs and the other side had NGK plugs.

The factory plugs in my V6 Camry were 3Denso and 3NGK

My 2001 Sequoia with the 4.7 V8 was this way as well.

the toyota fj was built like that

I’d be curious if true because watching a Toyota Highlander YouTube rear bank is more difficult may be a case where dealer only did one bank of a transverse V6. For the factory do do things like that seems less likely

If these are wasted-spark ignition systems, it's possible the factory specs double-precious-metal plugs for one bank only. In wasted-spark systems, the spark plugs are fired in pairs. Current flows from the centre electrode to the ground electrode of one spark plug, and from the ground electrode to the centre electrode of the other plug.

The precious-metal ground electrode is only required on one plug of each pair (3 out of 6 in a V6).

I would guess a single-precious-metal plug costs the factory slightly less than a double.

Multiply that by three plugs per V6 x millions of engines, and it makes sense.

 

[Sayjac]

First say, I don't think you can go wrong with either. Some years ago, when I did my 3.0L V6 Accord, Denso was OE (all) but I replaced with NGK. I'm just partial to NGK plugs, always had good results. Unless price significantly less for Denso, 'I' would use NGK. I purchased mine from AAP because with online discount code at time (25%) it was best price and same day pick up. I cross shopped RA but with shipping they were more. Might be different now.