2006 LS430 pulled the original plugs at 160,000 and they looked quite good, but probably should replace. Plugs were NGK IFR6A11, but I see they don't make them anymore. Any suggestions on correct replacement.

 

Replaced mine with Denso Iridium part IK20

 

160k on spark plugs.i change mine every 50k miles.

 

Spark plug replacement interval is 120,000 miles per the maintenance booklet. They might be considered lifetime if not for the emissions compliance requirement. My original spark plugs looked like new when replaced during the 120,000 mile service and the car didn't run any differently with the new plugs.

Maybe I'm odd but it never crosses my mind to not follow a car manufacturer's maintenance schedule.

 

i do all maintenance myself so $50 inplugs makes me sleep better.

 

Hey, we each baby our cars in our own way, but changing iridium plugs every 50k is like eating 1/2 an apple and throwing it out, then moving to another apple. Just not necessary. . DIY at least makes it less expensive.