joshua777

I hate to bring up an over saturated topic, but I found this to change a lot of things and figured I would share. For years I have been using NGK Iridium IX Spark Plugs (BKR5EIX-11) in my 1999 GS300, 196,XXX miles. However, about 2 months ago, I realized that these were the WRONG plugs for the GS300. I was doing work under the hood and realized a sticker I have never looked at (pictured below) and it got my attention. Checked the owners manual, only to find that I have been using the wrong spark plugs for the last 12 years or so?!?! The owners manual calls for platinum twin ground electrodes, or NGK Laser Platinum (BKR5EKPB-11). Not only was I using iridium instead of platinum, but I was also using single ground instead of twin ground. It clearly states to ONLY using platinum plugs for the GS300 and ONLY iridium plugs for the GS400. I mean, it even has an "X" through the single ground. The twin ground platinum plugs are pricy, $60 for 6 NGK ($1 each), or $45 for 6 DENSO. There are countless forums suggesting the using of single ground iridium plugs for the GS300, so hopefully this can help some people out. Heck, even O'Reilly's doesn't know that you need twin ground, they offer you single ground. I know it is pricey but my MPG went from 16 combined city/highway, to 24 combined city/highway after the switch, highway is at 75-80 mph 90% of the time. Not only this, but the new plugs gave me more HP/TQ, way more punchy, fixed a stutering problem I had around 35-45 mph, and the other plugs caused my alternator to fail prematurely. All things that I had written off because of the age of my car. After the experience with the new plugs, and what the owners manual had to say, safe to say I won't be using anything else.

NGK Plugs (what I use):
DENSO Plugs (have not used):

Mr Jokster

iTrader: (8)

My oil cap says only use 10-w30... I don't.

Been using singles for ever and get 20mph on an almost 300k engine. I don't see why its necessary to actually stop; they still work

MikeFig82

iTrader: (13)

I think it's the coil packs cant handle the new plugs. They are so wore out pretty much.

I ran copper plugs for about 2 months on my old gs400. No problems.

Later on I bought coilpacks from Rockauto and the denso iridium stock plugs. The car ran perfectly for 4 years. Close to 290k. Still ran like a beast.

2013FSport

iTrader: (2)

To meet the service interval in the maintenance manual the grade of precious metal plug matters.

If the owner knows a copper plug only lasts 10,000 miles great. But if no one knows, well now you have compromised the ignition and emissions which in the USA violates the Feds standards....

Gap and heat range matter more than ground straps. After that its about longevity.

joshua777

eicca

My GS400 has that twin-electrode sticker on the hood. However I know the front end was rebuilt many years ago so I wonder if it’s got a GS300 hood on it and nobody took that sticker off when they added the 1UZ stickers.

Letsride

To clarify....the 400 uses Iridium. The op is talking about the 300

joshua777

Yeah that would definitely make sense, because the only difference between the two is the engine.

joshua777

Yeah, I use 10w30 in the summer, because in the owners manual it states that it is okay to do so. I mean obviously my GS300 has ran for the last however many years just fine on iridiums, but there was a pretty drastic difference when I realized an issue and tried out the twin electrode platinums. If there was no difference, I would not have posted this and continued with iridiums.

SaiyanGS3

iTrader: (8)

The plugs changed after 2000 on the 300 iirc. Well known

TW99GS300

When I got my GS I ran PK16TR11 but then swapped to Denso iridium IK16. Feels much more responsive than the PK16TR11 that the manual recommends.
Spark plug tech has advanced over the years. Just because the owners manual suggest a specific part doesn't mean you can't interchange it for something else.
Besides, under that hood is a 2jz after all. You have plenty of options.

GS300ENTHU

That's on your model year car. My 2004 gs300 states "Your engine is fitted with iridium-tipped spark plugs".

lastguy

nonsense to me. My 05GS300 originally uses single ground one, most latest spark plugs also single grounded. I have 145K now.
it might be early model of your cars. so don't say gen2, just say 1999.

uhhnotsteven

For anyone reading this in 2023, This reply here seems to be true. I even searched online for my cars owners manual (2002 Lexus GS300) and it specifically says "Your engine is fitted with the designated iridium–tipped
spark plugs." with a picture of a single ground electrode spark plug my suggestion is that you do the same. Ngl this post gave me a little bit of anxiety while shopping for some spark plugs lollll