Should I change the spark plugs?
 

I just got an '04 LS430 and it has 111k miles. I've looked through the online service records to make sure the spark plugs haven't been done and I don't see where they have been. I know that at the recommended change is at 120k but I've had friends suggest to not worry about changing them as long as the car is running good (which it is).

I'm leaning towards just changing them because I can get them off Amazon for under $7 each and I would change them myself.

Just curious what others take about changing them? Do you think I would notice any change with anything like gas mileage?

yes change the plugs:thumbup:

change the plugs. manufacturer says plugs last 62,000 miles, not 120,000. I changed mine at 95,000 and it is a VERY BIG improvement. you will feel the difference.

may have been changed already. you can always remove one to inspect but if you want to do preventive maintenance then you can change all 8 out.

When you change them you will see it was needed compared to new.

my plugs after 123k miles for reference.

https://i1030.photobucket.com/albums...pse9f289f3.jpg

https://i1030.photobucket.com/albums...ps5d026557.jpg

https://i1030.photobucket.com/albums...ps310ecef7.jpg

https://i1030.photobucket.com/albums...ps477f6973.jpg

https://i1030.photobucket.com/albums...ps3f32769e.jpg

Wow... those are great, detailed pics.... and proof for sure they need to be changed. Lots of crap build up on them.
Thanks for sharing.

Some amazing photos. Did you run a lot of cheap gas in the car? Like 87 octane or just dirty fuel. Those little particles on the porcelain and electrode look like pre detonation or could be just dirty fuel.

The plugs lasted a long time but, change them at 60 to 70 thousand miles. The motor will run better.

Loren

Do you think it matters if the owner (me) always uses Chevron and even before added Techron with other fuels? My car runs like a clock with 118,000 miles but don't mind changing the plugs if it will make a difference in performance or gas mileage. What do you guys think?

Caverman, the service records mean little to nothing except when speaking about the timing belt or major oil leak service... IMO... my records didn't even list that the plugs were changed and they were. Your plugs likely have not been changed.

Here's my prescription for your trouble:

Pop the hood, take the engine cover off(10 mm socket), pull 1 plug from the drivers side of the engine and inspect it (plug socket and universal joint extension so you can get your angles right). If it looks new then decide if you like your car. If you like your car then pull the air intake plastic crap off the passenger side of the car and pull the plug closest to the firewall on the passenger side and inspect it. If it looks new then put everything back. Should take you about 20 mins total, unless this is the first time you've removed the plastic intake(just a few screws). I recommend you look at every plug because it's just too easy.

Plugs are quite easy to do on this car, so don't take it to a mechanic.
I think you might put 1 drop of oil on the threads to keep the plug lubed when you put the new plugs in, but someone else might say otherwise. Very lightly tighten the plug down.. just barely at around 12lbs of pressure. Make sure you get the OEM plugs.. iridium.
These?

Ordered a set off Amazon last night. I figure if I'm going to pull them to look I might as well go back with new ones for only about $60. I'm hoping to keep the car for a while so I definitively want to keep it maintained well.

I've only got one or two other issues I will have to deal with the car to get it to where I want it. For the most part it's in really good shape.

Mine were just a bit better at 112k miles. Less corrosion on the threads. They should be done with the timing belt / water pump.

There are a couple of NGK plugs listed. There is a thread I made a while ago where we discussed the difference. One of the NGK's are only rated 60k I believe. I got mine from the dealer as it was the same price with discount. Remember, don't treat the plug threads with anti-seize. This is the old style of thinking. Lexus and the manufacturer specifically tell you not to. Then torque it properly.

Edit: Found that thread, has some good info in it.

https://www.clublexus.com/forums/ls4...-tomorrow.html

If the car runs and feels great then I would not replace them until at least 100K... In your case, I would do it. Please take a photo of your plugs and post.

I have run nothing but 93 octane in the car since I've had it, with the exception of maybe 2 full tanks of 89 (due to stations not having 93).

Almost 119,000 miles on my 01 LS430 with what I believe are the original plugs. Accelerates like a rocket ship and idles as smooth and quiet as a church mouse. I'm not running out to replace my plugs as I know that at this age and mileage there might be something cropping up that might need my attention. However for a luxury car that I have owned for almost 5 years, this car has not disappointed me. Oxygen sensor, Valve cover gaskets, and front struts were the majority of my expenses. Not bad for a car with 118,000 miles. I'm a happy camper. Yes I'd like to own an Audi A8, but no..... I don't want to have to pay and fix it.