1990LS400

2000 Ls400 120k Mile Maintenance Last Week -

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Mechanic "Fred", at the indie repair shop that has maintained our Lexus and Toyota cars for about the last 14 years, did the 120,000 mile maintenance service on my 2000 LS400 last week.

The car has been maintained "by the book" or a little better since new ... by the original lessee who drove it from new to 36,000 miles and then by me after I bought it in 2003 at 38,000 miles from the indie used car dealer who bought it at auction and drove it for 2,000 miles as his personal car.

The photo of the original factory installed Denso iridium spark plugs is a little fuzzy but I can tell you that there is no sign of deterioration or burning on any of the eight plugs after 120K miles of use. The engine doesn't run any better or have any more power with new spark plugs so it appears that there is a healthy margin between the 120K normal replacement interval and when deterioration of the plugs begins. I suspect that the original spark plugs would have been fine at 150K miles but, like I said, I maintain cars by the book.

The original factory installed rear brake pads could have gone longer than 120,000 miles. The pad with the least thickness is at the far left of the photo and it was down to slightly less than 3 mm. The other three rear brake pads had between 3.5 mm and 5 mm left. I was surprised at the amount of variation in remaining pad thickness. I check brake pads on the car every 5,000 miles or so but I do a visual check and rarely use a gauge since I'm a "metric man" and know what a millimeter looks like.

The engine air filter and A/C filter look tyically dirty after 30,000 miles of use. I usually remove the A/C filter every 5,000 miles while doing an oil change and knock the debris from it.

Fred did all the other maintenance and inspections listed for the 120K mile service including replacing coolant and brake fluid. Although not required, I had the transmission and differential fluid changed as I do every 30,000 miles. For my year and model, a transmission fluid change is never required under the normal service schedule and only every 60,000 miles under the "special operating conditions" schedule. A differental fluid change is never required under the normal service schedule but is required every 15,000 miles under the "special operating conditions" schedule. My LS certainly isn't used routinely used in the "special operating conditions" listed in my car's maintenance manual so changing the transmission and differential fluid every 30,000 miles is probably overdoing it.

Total cost of the 120K maintenance was about $690 not including tax and also not including an oil change and tire rotation since always do those myself.

The rear brake job, including rotor resurfacing was an additional approximately $230.

My purpose for creating this thread is to confirm that maintenance parts like spark plugs and brake pads can last a long time and to give information that might be helpful when looking for someone to service your cars. I have long noticed that many dealers and repair shops recommend wildly overmaintaining Lexus cars under what I would call "fantasy maintenance schedules" and apply the same fantasy maintenance schedule to all Lexus models even though there can be significant maintenance requirement differences between models and model years.

Just following the recommended "normal use" service schedule can help these cars last a very long time.

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Great stuff. It’s really pretty remarkable what electronics have done for engines in the past few years. Modern coil over plug and ECU controlled firing leads to a very accurately timed spark and a particularly hot one (less impedance from coil to gap without a rotor, distributor, and long wires and the faster switching edge on the coil primary). Long gone are the days of the once a year plug set, breaker points, and rotor "tune up".

Perhaps I am dating myself a bit….

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Great stuff. It’s really pretty remarkable what electronics have done for engines in the past few years. Modern coil over plug and ECU controlled firing leads to a very accurately timed spark and a particularly hot one (less impedance from coil to gap without a rotor, distributor, and long wires and the faster switching edge on the coil primary). Long gone are the days of the once a year plug set, breaker points, and rotor "tune up".

Perhaps I am dating myself a bit….

I have been thinking about changing the original plugs in my 98 sometime this spring but with 96k miles on them and the report from Jim, maybe I should wait. The engine runs great and the gas mileage is way up there.

The only concern I have with plugs (in general, not on a Lexus) is that I had heard horror stories of the threads "welding" into place in the head if not periodically removed. Probably an old wive' s tale. :rolleyes:

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I have been thinking about changing the original plugs in my 98 sometime this spring but with 96k miles on them and the report from Jim, maybe I should wait. The engine runs great and the gas mileage is way up there.

The only concern I have with plugs (in general, not on a Lexus) is that I had heard horror stories of the threads "welding" into place in the head if not periodically removed. Probably an old wive' s tale. :rolleyes:

You make a good point 100k is a lot of heat/cool cycles. I think they must use an anti seize grease at the factory but that may be all but dried out several years later.

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I have been thinking about changing the original plugs in my 98 sometime this spring but with 96k miles on them and the report from Jim, maybe I should wait. The engine runs great and the gas mileage is way up there.

The only concern I have with plugs (in general, not on a Lexus) is that I had heard horror stories of the threads "welding" into place in the head if not periodically removed. Probably an old wive' s tale. :rolleyes:

Randy, if your 98 LS400 is still on its original spark plugs, they may be platinum instead of iridium. I think 1999 was the first model year iridium plugs were used in the LS400 so they could extend the change interval from 90,000 to 120,000 miles. Not that platinum plugs couldn't last more than 90,000 miles -- the platinum plugs on the 90 LS I had looked darned good when they were replaced at 90,000 and 180,000 miles.

Regarding "welding" ... why don't we have young wives' tales or old girlfriends' tales?

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I realize that this is an old thread but the issues are frequently raised among owners.  My '98 LS400 came from the factory with iridium plugs and this was also indicated in the owner's manual. At 150,000 miles, the engine starts quickly and runs well.  Two plugs were removed and inspected by my mechanic last year.  He pronounced them in very good condition with gaps still within factory specs.
 I did not replace them.  I did change the differential fluid and used GL-5 w90 from Miller's Oil. A call to Lexus gave a response that no substitute was authorized.  The old fluid appeared to show only modest deterioration and there were no fragments on the magnet.  So, I probably didn't have to do the change.
 Every other engine oil change (@5K..usually conventional oil) I do a transmission drain and fill replacing the 2 qts. that come out when the plug is removed.  Toyota T-IV, of course. Replaced tires this year (Sumitomos and like them).  The car continues to be a joy to own and to drive.  Clearly superior to the M-Bs provided by my company.

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I'm still around although I don't look at this forum very often since selling my 2000 LS400 in 2014.  Yes, the 98-00 LS400 is a wonderful vehicle and infinitely more enjoyable to drive than the new air suspended LS460L that I test drove a few years back.  I'd still have my 2000 LS400 if it hadn't started to corrode, if I could have updated it with modern safety features and/or if I had enough garage space to keep it as an occasional car.

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Hay Jim, I just had my plugs changed at 200k, for the first time, and it revived my engine completely, I could not believe how it had gone down, I just got used to it as it "died".

I also had the WP/TB and ALL bearings and seals on front of engine, exposed & internal, with all 3 engine mounts and valve cover gaskets plus tube orings.

It drives like new and no corroding here in Texas. I put 17" 2001 wheels with 235 55 michelin lattitude tires & 4wheel align.. so now it should last my life time.

good to hear from you..

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