Anyone has used iridium spark plugs on 1st generation of LS400 ? Any performance or mileage gain that justifies the additional cost ? Both Denso & NGK have iridium spark plugs but I don't know if they're compatible with LS400. Any idea ?
tvd51

 

there is no clear advantage for using iridium plugs, if the manual states to use double platinum, using iridium will only be a waste of money

 

Yup. What p said. Save your money, platinum plugs cost enough as it is.

 

NGK has two types of platinum spark plugs:

- Laser Platinum: (recommended by Lexus manual) The platinum tips on both ground and center electrodes and they're welded using laser.

- G-Power Platinum: platinum tip on the center electrode only and not laser welded, but it costs less than half of Laser Platinum.

Anyone has used both types of these spark plugs ?

tvd51

 

Since I'm about to do a tune-up a needed to buy spark plugs. I was all set to buy the NGK platinum ones when I saw that the iridium plugs were about the same price. I ended up getting the NGK IX iridium plugs, we'll see if they're better.

http://www.ngksparkplugs.com/product...420&country=US

 

Earl, when you install the new spark plugs, try this hot rod tip:
Try different plugs until you have the electrodes opening facing the intake valves ---> more direct exposure between spark and fuel/air mixture ---> better combustion ---> more power.
tvd51

 

I replaced the spark plugs with NGK G-Power Platinum (the less expensive ones compared with Laser Platinum). The car runs better, partially because the old plugs were under-torqued.
Earl!, what happens with your iridium plugs?
tvd51

 

It's cold here in MN and I don't have access to a heated garage, soooo I have to wait until it warms up .