RanGer498

ok i want to change my plugs but my questionis this in the owners manual they say to use only a iridum-tippd spark plug and that our motors are fitted with twin ground electrode spark plugs and have a pic of a single grounded spark plug and say not to use this type. (page 229 in the owners manual 1998 book)im not sure if they mean that the gs300 and gs400 can only use twin ground electrode spark plugs and not single grounded spark plugs or only the gs300.

(recomended spark plug as per here www.sparkplugs.com ) i was told it looks like the pic below here https://www.clublexus.com/forums/sho...hreadid=119178

is it ok to use this plug or am i looking at the wrong plug for my gs 400?

thanks

SeattleGS400

iTrader: (1)

The Denso Iridium is the right plug to use in the GS400 (it came as the factory plug). Even the newest GS300 uses the Denso Iridium plugs. They used to use the twin ground electrode in the earlier GS300, but now, I believe, all Lexus cars use the Iridium plugs as OEM parts.

RanGer498

thanks!

bitkahuna

iTrader: (20)

How hard is it to replace the plugs on a GS400? I've heard it's a biatch.

SeattleGS400

iTrader: (1)

Surprisingly, it's not too bad to do. Taking your time, about 2 hrs total. Other than removing your engine cover (4 simple bolts) and the plastic air intake to the throttle body (a couple of bolts, and 3 small rubber vacuum tubes attached to it), it's just the ignition coils, then each plug.

The plugs are easy to get out, however, the 2 rear plugs on the driver's side engine bank requires a little more care due to space limitations.

Tools required: spark plug socket, a couple of extensions, a set of pliers (to remove the vacuum hoses) and a rachet (and a torque wrench is highly recommended for final tightening of the plugs)

Be sure to get some dielectric grease (for the interface of the rubber part of the ignition coil and spark plug) and some spark plug anti-seize compound (for the threads of the spark plug, so it does not lock up into the engine block).

If you need more complete info, I can post more--or do a search on CL. I'm sure others have posted this procedure in detail before.

RanGer498

well mine should be here this week lets see how it goes.