Spark Plugs

[philg]

I recently bought a 98 LS400 and it is due for the 120k mile service. I am doing it in bits and pieces. I have done the air filter, oil, and am flushing the brakes. How important is it to do the spark plugs every 30k miles? Also how important is it to change the transmition fluid and is there any way to tell when it is ready for a change (discoloration similar to engine oil? or is there no such sign?)

[cardona6569]

I would not play with the transmition fluid, unless you want to spend 3,000 grand on a repair, change it as the manual states, or replace couple of quarts at every oil change, the ones you can drain with the drain of the tranny, but even so you will need to go in there at 100,000 or 150,000 to replace the filter, which involves removing the pan and resealing it with sealant, even as I think they sell some gaskets but these are no OEM. Second I would replace the sparks at 120,000, these engines run hot, thus creating a lot of carbon in the plugs and intake, so your plugs if not replaced will start to give problems. Third go to the UK forum and look how to clean your massairflow sensor, it is one inexpensive maintenance that will save in a lot of headaches later, it will cost you to do like 5 bucks and maybe half hour work.

CPR

[philg]

Thanks for the advice. I am still not sure if the plugs or transmition fluid were done by the previous owner. All recomended factory maintenance was done until april of 2006 when the car had its 105k mile service. From that point all I know is that the oil has been changed. Is there any way to determine if the transmition fluid is fresh? I can usually look at the oil on a dip stick and notice wether it is a clear/golden color or if it has been a few thousand miles and it is a bit darker, is there any similar test for the ATF? When I checked the ATF level it was perfect and the liquid on the dip stick was a red color. Also any similar method for checking the plugs?

[RCRFAN3]

I also have a 98 LS and it needs plugs every 90,000 miles. I change the transmission fluid with every oil change done at 3,000 miles. I use Valvoline 5W30 which is the factory recommended oil. I remove the drain plug for the transmission fluid and replace 2 quarts of Toyota Type IV. It is very important to use only Toyota brand, no exceptions. I know this is overkill on the trans, but a Lexus certified mechanic does the same on his personal car and recommended it. I have 130,000 on my car and have never had a problem.

[92Lex]

Change your transmission fluid everytime you change your spark plugs (30k). No, the transmission filter doesn't really have to be "replaced". You can just take it out and clean it with clean trans fluid, then replace the pan with a new gasket.

[cardona6569]

I have never changed the filter, Is that filter not made of paper, is it metal? SEcond, do you know if in the 98 every spark plug on top has a coil? CPR

quote name='92Lex' date='Dec 29 2006, 03:39 AM' post='220662']

Change your transmission fluid everytime you change your spark plugs (30k). No, the transmission filter doesn't really have to be "replaced". You can just take it out and clean it with clean trans fluid, then replace the pan with a new gasket.

[92Lex]

What's the actual build date of your car? 8/97-2000 vehicle's use the coil on plug system. Yes, your trans filter is just a metal screen type of filter. You can just clean it by running some brake fluid through it, but it's a cheap part anyways. Not much damage on your wallet if you did decide to replace it.

[cardona6569]

Then the Dealers in its aim to flush it, is more than correct since is just wire, when it is flushed it all should become clean. CPR

What's the actual build date of your car? 8/97-2000 vehicle's use the coil on plug system. Yes, your trans filter is just a metal screen type of filter. You can just clean it by running some brake fluid through it, but it's a cheap part anyways. Not much damage on your wallet if you did decide to replace it.

[SKperformance]

Flushing the tranny will not make the filter clean if it did it would make the particles start to float in the tranny all over again and defeat the purpose of the filter in the first place. The screen mesh only holds back large particles not small ones. Also the magnets do need cleaning to remove any metal it catches.

I use high end synthetic oil for my engine but only Toyota tranny fluid as it is the best for it.

Using good ol copper plugs work great i bought iridium's from NGK and found no difference luckily i bought them cheap other wise it would have been a waste of money.