ur2slow1

So my dealer tells me that the factory replacement plugs for my 2000 ls are not Iridium, does anyone know if this is true. I see a lot of guys using iridium's, what should I do ?? Thanks

Kansas

Is there any reason not to use the type of spark plugs that are sold by Lexus for your 2000 LS400? I doubt if some other type of spark plug is going to make your car run better.

The spark plug change interval for the 2000 LS400 is 120,000 miles. Mine are still fine at 108,000 miles.

19psi

the best spark plugs for performance and mileage are the cheap copper plugs. that's not what the car comes with for maintenance interval reasons but copper plugs are the best contrary to all the advertising hype BS. i'm sure there are some for the LS at any decent parts store. just ask if they show an NGK or Denso copper plug application.
i can explain why if you want to know.

PureDrifter

iTrader: (10)

not related but i'm interested, more pls?

19psi

haha, ok...
so we know that the bigger the spark , the more power, and mileage too if driven sensibly. (efficiency).
ok then.... every time the spark plug sparks, a tiny piece of the electrode comes off and makes the spark. copper is softer than iridium or platinum. it's a better conductor. look up the conductance of copper vs. iridium and platinum.
so it stands to reason that a more powerful spark comes from a copper plug!
the reason we dont' see copper plugs anymore is longer maintenace intervals. since cars became harder to change the plugs on(V6 fwd in particular), it's beneficial to make the sp. plug interval 100k miles or more so that the customer doesn't have to pay all that labor for a simple tune up. iridium and plat. last so much longer than copper that they are used for that purpose.
look at any race car, anybody who knows what they are doing uses copper plugs. of course i'm talking semi streetable race cars. i dont' know wht top fuel cars use or funny cars or anything like that. i'm talking 9 sec. turbo eclipses, supra's, etc.