gebo

when do you change the spark plugs in a '98 LS400? the book says 60,000 miles based on some emissions thing. When I went to the local Toyota dealer to get the plugs, the parts mgr said , "You already got 120,000 miles on your car?" I told him only 60K. he then asked my why I was buying the iridium plugs because they replace those plugs in Toyota trucks at 120,000 miles. Where I live they don't do emissions tests and I am "only" concerned with performance. will changing "these" plugs at 60k make any noticeable difference in my performance, mileage, etc.?

Lvangundy

H'es going by the book it sounds like...

There some people who recommend spark plug changes even sooner than that just to help the engine run smoother. I'd say go ahead and change them now. If anything you may notice a 1 MPG increase. I just changed mine in my 90 LS and I got about a 1MPG increase, and smoother RPM movement. They were last changed in 98 at either 65k or 85k miles.