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The 2001 RX owners manual lists Denso SK20R11 for the standard replacement plug. The Denso website along with many dealers list the K20R-U11 as the OEM plug with the SK20R11 listed as a long life plug and the IK20 listed as a better performance plug. I know all will work but can anyone confirm what plug number is in the engine from the factory. I now have 125K on my original plugs and have been pleased with their performance and life. When I do the switch I would like to use the exact ones even if another number claims longer life, better performance, better econmy,etc.
When I changed the original plugs in my DIL's '99 RX at 97K mi. it had NGK IFR 6A11's in it. They looked like they had 15K mi. on 'em. If I had pulled 'em before I got the new plugs. I'd have never changed 'em. I still have the plugs (don't know why, just couldn't throw plugs away that looked so new) and they are some of the most amazing plugs I've ever seen. Car has 170K mi. on it now and I bet the plugs would still be functioning perfectly.
When I changed the original plugs in my DIL's '99 RX at 97K mi. it had NGK IFR 6A11's in it. They looked like they had 15K mi. on 'em. If I had pulled 'em before I got the new plugs. I'd have never changed 'em. I still have the plugs (don't know why, just couldn't throw plugs away that looked so new) and they are some of the most amazing plugs I've ever seen. Car has 170K mi. on it now and I bet the plugs would still be functioning perfectly.
As I posted before, I have a copy of a Technical Presentation made by Denso engineers detailing the development of these iridium plugs. Their objective was 200k miles before performance started to deteriorate. According to their data, they accomplished their goal. I do not think there is any reason to change these plugs as a maintenance item. Of course it is statistically possible that one of these plugs will fail prematurely and need to be replaced, but that will be rare. I think I had around 100k on my wife's RX when I changed the plugs (they were Denso's) and the old electrodes looked almost identical to the new ones.
I changed my plugs at 160k miles, and they looked pretty good. They could have easily made it to 200k miles. Which is how far I was willing to take it, but I got a good deal on the plugs so I decided to just change them.
As I posted before, I have a copy of a Technical Presentation made by Denso engineers detailing the development of these iridium plugs. Their objective was 200k miles before performance started to deteriorate. According to their data, they accomplished their goal. I do not think there is any reason to change these plugs as a maintenance item. Of course it is statistically possible that one of these plugs will fail prematurely and need to be replaced, but that will be rare. I think I had around 100k on my wife's RX when I changed the plugs (they were Denso's) and the old electrodes looked almost identical to the new ones.
Art,
When I changed the plugs at 97k mi. they still gapped the same as new. I have read that Iridium is the hardest metal known to man. It certainly seems to be since it never seems to wear. I know this is apples and oranges but I remember when I was a young'un (a looong time ago) I drove Olds 88's (owned 4 of 'em) and I did drive pretty fast but I HAD to replace the plugs every 10K mi. They were BURNED up! Oh how times have changed.
Once the manufacturer recommends certain makes and types, during manufacturing they can use either. It all depends what they have in stock. You can only be sure once you pull them out.
I would suggest to get NGK irridiums ... pre_gapped and long(er) life. 100k should not be a problem.
Remember to put anti-sieze and finger tight all the way and use the torque wrench at the end.
Salim
so the original plugs could be denso or ngk? i pulled one a few days ago and it was an ngk. made me wonder if they had been replaced before.
sounds like most here don't think changing plugs as routine maintenance is necessary and old plugs produce no ill effects?
Changing plugs is still a part of routine maintenance, its just that the cycle starts at 100k miles these days because of improvements in the plugs and ignition systems.
I suppose you could start doing it at 30k miles if you really want to, although you no longer have a cap, rotor, and points to change, so to make up for the time that would have been saved you might as well start changing your oil at 1000 miles and air filters ever month to give yourself something to do .
Also, I just skimmed over the thread so I may have missed it, but no one seems to have brought up replacing the plug wires. For most modern cars the wires will wear out and start arcing before the 100k+ mile plugs become a problem and would need to be replaced.
I finally decided to change the plugs and coils o my 2002 RX. After reading on this procedure for over a year, I decided to let my mechanic do the actual work. My hands are too big and there is just too much mixed information - remove cruise control, remove intake, no don't do this just do this or that. I didn't want to screw anything up. But here is what I did do and what I recommend for you: Go to dense website or sparkplugs dot com (same company) and but buy 6 coils and 6 plugs. Change the coils along with the plugs. It's not worth it to just do the plugs unless you are incredibly adept at this procedure. DO NOT use any aftermarket or Bosch plugs. Use Denso SK20R11 plugs and Denso 673-1301 coils, period. I have read many, many horror stories about using aftermarket parts and it is most definitely not work it.
Attached are my 6 plugs at 149,600 and a copy of the invoice from spark plugs dot com. A few look OK but two of them are heavily fouled. I definitely notice a difference in acceleration and my gas mileage has improved 25% so i would say 150,000 is the max you can go before a change. Good luck my 1st Gen RX brothers!
I finally decided to change the plugs and coils o my 2002 RX. After reading on this procedure for over a year, I decided to let my mechanic do the actual work. My hands are too big and there is just too much mixed information - remove cruise control, remove intake, no don't do this just do this or that. I didn't want to screw anything up. But here is what I did do and what I recommend for you: Go to dense website or sparkplugs dot com (same company) and but buy 6 coils and 6 plugs. Change the coils along with the plugs. It's not worth it to just do the plugs unless you are incredibly adept at this procedure. DO NOT use any aftermarket or Bosch plugs. Use Denso SK20R11 plugs and Denso 673-1301 coils, period. I have read many, many horror stories about using aftermarket parts and it is most definitely not work it.
Attached are my 6 plugs at 149,600 and a copy of the invoice from spark plugs dot com. A few look OK but two of them are heavily fouled. I definitely notice a difference in acceleration and my gas mileage has improved 25% so i would say 150,000 is the max you can go before a change. Good luck my 1st Gen RX brothers!
Is there any consensus or professional word on using anti-seize on spark plugs? I called Denso and they said 'No.' But I have a 2000 RX 300 that I acquired recently and have run into a seized spark plug on Bank 1 #5. Getting this out will be fun.
Someone in this thread commented, "Don't forget the anti-seize." And I've read there is a legal reason that there is advise against it.
But I'd like to know the answer strictly from an auto engineering point of view. I've replace five of the six with Denso Iridium spark plugs and they will be there for a long, long time. Anti-seize seems a matter of common sense but it's always
worth asking the pros.
Is there any consensus or professional word on using anti-seize on spark plugs? I called Denso and they said 'No.' But I have a 2000 RX 300 that I acquired recently and have run into a seized spark plug on Bank 1 #5. Getting this out will be fun.
Someone in this thread commented, "Don't forget the anti-seize." And I've read there is a legal reason that there is advise against it.
But I'd like to know the answer strictly from an auto engineering point of view. I've replace five of the six with Denso Iridium spark plugs and they will be there for a long, long time. Anti-seize seems a matter of common sense but it's always
worth asking the pros.
It is one of the questions that you will not a unanimous answer. Some will insist on using it and some will say skip it. I don't recall seeing the service manual talk about it. I am **** about proper torque, so I follow that . Regrettably for the bank 1, I had to go by feel only as I replaced mine without removing the intake and there is no way to get a torque wrench on them.
Now getting scientific [and you will get a unanimous opinion on this] .. once you put thread anti-lock the torque spec has to be adjusted as the thread to thread friction is modified/reduced by the antilock.
Practical advice regarding RX:
Make sure the engine threads are clean [use a thread chaser without damaging the threads] and when you install the new plugs, thread the bank 2 by hand till they bottom out. then use a toque wrench and count revolution/angle to get to the spec. Then get a feel of how tight they are. Use this angle/feel to tighten bank 1 plugs. You need to crush the metal gasket. If you feel you have gone slightly over, don't back off. Remember the spec is in In-lbs and not ft-lbs.
08-11-12, 01:10 AM
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