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ls 400 service booked at specialist plugs? filters?


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My 400 is booked in for a long overdue service. It was last serviced in 2012 at Lexus, although that was only 6000 miles ago. I am having the oil and filter changed and the air filter changed. The spark plugs were changed in 2008, around 12000 miles ago. Is it worth changing these? If so, what is the correct spec for a 1999 ls 400? I have searched the forum but not found anything. I look after my cars well, and am not happy with myself about leaving it two and a half years since I bought it. However, sometimes other things take over in life.

I went to the Castle Howard car show yesterday, the highlight of which was the Spitfire air display. I was disappointed with the fuel consumption, which seems to have taken a sudden dive. It may, or may not be linked to some work carried out last week on the air conditioning system. I'm wondering if something was disturbed. Usually on a good run I can achieve 30 or late 20s, but yesterday I was struggling to get above the low 20s. I noticed from setting off that the current mpg seemed even lower than usual. The air con specialist was very good, and seems to have fixed an issue that two other garages have failed to resolve. I now have a cool 1.7 degrees C at the vents. An overnight pressure test (which had to be done twice, as the first revealed a iny leak at a seal).has raised confidence that it is now sorted. I am happy to recommend the air con specialist, also an auto electrician, and based in Rotherham. After next week, i probably will be happy to recommend tha lexus specialist, as he is a nice guy and seems very knowledgeable.

So, questions, spark plugs need changing after 8000 miles and 8 years? if so, what spec?

Oil / air  filter, Lexus or Mann? the specialist says he asks the customer, and uses whatever they prefer, which is a good approach, I think. Are the lexus oil and air filters better?

As always, very grateful for any advice

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Hi Harry

I've a 2000 LS400 and have plugs ready for my toolkit and time: they are Denso iridium SK20R11 bought from Opie Oils for £57.10 including p&p. Retail prices vary of course and they can be around the £70-80 mark. NGK, Bosch, Champion also do the iridium equivalents.

In my case I can't see any evidence of my plugs being replaced, so worse case this is 16 years and 77,000 miles or best case before change of owner and records began 10 years and approx 42k miles. These are long-life high quality plugs and I have read of 80-100k miles as acceptable before a change. However, one might want to factor in time related deterioration and whilst your mileage is minimal, eight years is a long time...I would personally replace them. But it is not cheap.

I opted for the Lexus oil filter as they are reasonably priced but I did baulk at the air filter and went for a Blueprint. As I did the work myself it does make opting for Lexus parts easier as I'm not paying labour charges and then the VAT on that. For example I would stick to Lexus transmission fluid and brake parts but I fitted Gates pulleys, waterpump, tensioners and belt. To sum up I believe it is preference/budget and not necessarily in that order! I wouldn't buy unbranded and I'm ok with quality replacement parts even if I have to get them from the US.

As for your fuel consumption: well I assume you reset the trip...or if so it did reset?  Any test drive and having the car idling whilst being checked and repaired by the specialist would reduce your average. In my case when doing my son's university run...superb on the motorway at decent speeds pulls the average up from very sub twenty driving I've clocked up in ultra busy urban environment if I haven't reset the trip!

Good thing is your car can be checked at the service for anything untoward. 

Good luck and I look forward to hearing how you got on. 

 

 

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Hi Simon

thanks for taking the time to respond. That's a good point about the time the engine was running during the work on the aircon, but I'm also looking at the mpg for the current tank of fuel, which was refilled after the work was done. Even the current mpg display, which I rarely check, seems lower than usual. I'm not sure the car is picking up as quickly as it should, but I hope a good servie will sort it out. I'll ask the specialist to give it a good check over. I've seen those spark plugs for around the £50 mark, a;though I need to make sure they get here bfore next Monday, and thanks for confirming the spec of those.

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Hi Hugh

The spark plugs are 60k minimum life and will not need replacing unless you have been using a mixture to lean or to rich .The fact they are buried safely in the combustion chamber protects them from the atmosphere.

I fitted a K&N filter for life when I got the Mark 4, it does what it says on the box.

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I changed mine a while back for Brisk and changed the Leads at the same time. Not sure that the leads were a good buy as one snapped easily when putting the cover over the RHS.  Had to re-use previous Lead.  I did notice a slight brown staining on perhaps two plugs around where the Ceramic part touches the steel thread piece. Moisture /condensation can sometimes gain access to plugs,(shorting?) so I was told. They were the plugs nearest to the Bulkhead. Otherwise the plugs were probably original and looked in good shape as regards burn.

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Plugs are good for 60,000 miles so I think you'd be wasting your money replacing them. Could be worth having the Ht leads checked as some of them are more likely to be breaking down.

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I rang the Lexus dealer for some parts prices and was told the recommended intervals for plugs wa 60,000 miles or 6 years. It has been 8 years and the car is not running perfectly, so I have decided to change them. I've ordered Denso plugs off eBay, but could easily have paid double that

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Hi Hugh,

I was in a similar situation when I bought my LS400 and I wasn't sure where to start. I collated quite a bit of information from various sources and made a spreadsheet that allowed me to fill in what was done and when so I could see which areas may need addressing in time.

When I am back home I'll add the file to this thread.

Mark

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I spent a pleasurable hour or so tinkering on Saturday morning. At last I changed my spark plugs.

I expected to see the original Denso plugs (?) but was greeted by a set of NGK iridium plugs that looked well worn at the sharp end. 

All done now.

I've attached a mini-guide for those that have never attempted it on a Lexus - or are curious. 

 

 :driving:

Changing LS 400 Spark Plugs.compressed (2).pdf

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Thanks. Well I am not sure as I don't think they're OE. Given my mileage is a validated 78k they haven't done monster miles but may be 10 years old. 

If they were OE then up to 16 years.

Perhaps the plug manufacturer is relevant? Maybe these can't do the 60-80k miles?

the photo is a bit harsh though, the plugs are tired but were working fine...

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