question about the best spark plug vs what you are told

the prevailing wisdom is its best to use the denso or ngk factory plugs in our engines but many mechanics I have had dealings with swear the AC autolite plugs wear better last longer in Toyotas and Nissans and (while im not convinced of this part) say they make the engine idle better.

my first 2.4 taco had ac plugs when I got it and it was running great with autolites but I replaced them any way thinking (and being told here) that factory oem plugs was better. I cant say I noticed any difference.

my 3.4 had the oem 2 prong plugs (3 ngk & 3 denso) and I replaced them with all the same denso brand 2 prong plugs.

the reason for this post is to get a discussion going as to what is the truth about what is the best plugs to use based on real life evidence from mechanics working on engines vs the "rule of thumb" stuff done by the average joe in his driveway "just because" that what people say to use, with no "real" proof one way or the other if either is better or not.

I suspect 4 cylinders are going to be different since they are single prong and the v6 uses 2 prong plugs. for this reason I am going to assume its more likely 4 cylinders might be where there is no difference other then the life of the plug.

now that there are 2, and even 3 prong plug options out there for most engines, are there better options for the v6 that will last longer or work better?

 

The "do it in the deive way guys" like myself trust the engineers at toyota that fully designed and built the engines in our trucks all starting with an idea of a motor. They know more about our motors than any mechanic that you will find. So why try and argue with someone that designed the motor? Run what they say. There is a reason they tell you to use certain parts over others. As for the autolight comment, autolight is oem ford I believe (correct me if im wrong). Ford is an american made motor not japenese. American plugs made to run in american motors dont run well in japenese motors. Its all over the internet of people trying it and having nothing but issues from it. Stay with OEM NGK/Denso duel ground plugs.

 

Autolites will seize in the head too without a good application of antiseze....i would never believe any talk of them out lasting a denso or ngk, or providing a better idle. Also neither of those plugs require and antiseze.

 

i cant say specifically, but have replaced many autolites, champion plugs in all types of foreign vehicles that are running like shit, replace them with denso, bosh or what ever is recommended by the manufacture and vehicle then runs great. plugs are the first thing you look at when diagnosing a shitty running engine. plugs usually replaced soon after they were installed and not worn out and gapped correctly...
been a tech for something like 10years at various places.

for the comment on them seizing to the head, yes it is common practice to put antiseze on plugs going into an aluminum head, being that plugs are steel and head being aluminum and dissimular metal corrosion happening.

 

What bry838 said. Some plugs don't need anti-seize.

From NGK 5 Things You Should Know About Spark Plugs

 

Ahh i forgot to mention that the antiseize can create an issue with over tightening, had actually forgot about that!

So basically there are multiple reasons to not use autolite in our trucks...

 

The only real way to know is to run a test on several different vehicles.

that have about the same mileage and are used in about the same way

Then most often any new plugs work better then old worn ones

I use the plugs from Toyota just because it is easier to pick them up when getting other goodies .

Toyota has them in stock where it seems most other places I get given the single prong plug because that is what the computer tells the counter person I need .

Now this may have changed it has been a few years

 

While I can't say I necessarily agree that the engineers that designed the engine know it best (I work in automotive manufacturing and engineers can be hit or miss) but they do have some stuff down. I've run NGK/Denso for the last 100K I haven't had any spark plug issues, same with my girlfriend's car running Motorcraft in her Ford.

Plus I can get whatever the dealership is carrying for around $2 each while the auto parts store will try to sell you iridium/platinum/unobtanium (whichever costs the most usually) as OEM or "OEM equivalent" for a good bit more.

 

Stick with what brung ya. Being Old, In those days yonder, Autolite (Motorcraft) were better plugs compared to others (In 383's, Hemi's and such) and had a higher heat spark and worked well with older engines. In my 2006 Mustang GT, I switched from Autolite to AC plugs because of the difference between 2 piece and 1 piece and a healthy dose of nickel anti-seize. Runs great tho the newsgroups moaned about QC on them, I checked them out before installation. Toyota is a different animal all together with different engineering and thought process in the design. I have stuck with stock plugs on the Taco and have never had a problem.

 

If you're expecting a night and day difference from 1 plug to the next you're likely going to be disappointed. Oem will always do the job, so we'll 98% of the non oem.

I've run most brands over the years, was more prone to getting the gimmicks when i was younger. Any differences were pretty negligible. The biggest change was always just getting rid of worn out plugs. As long as they create spark, theyll create fire. Now i use oem more often than not, is simpler.

Plus I'm cruising the beemer now and don't want to make it angry.

 

I had a denso plug from toyota lose the electrode. Into my cylinder and then out the exhaust valves. Engine is still good. luckily. It's hit or miss. but - I still run them. It's a V6 so as long as they are not worn down or gapped improperly whatever they recommend works.

 

There was a gal a while back that had the very same issue happen with either a denso or ngk! They had to do a rebuild however! Id be so pissed! I bet you lucked out kinda not ending up with any damage!

 

I kept the plug. Just in case. It's running like a top now. No noises. I had to use a magnet stick to get some of the shiz out of there. The coilpack boot was ripped to. I just wonder what caused all that. I'm thinking manufacture defect. Maybe I should send them a picture and a story

 

Couldn't hurt i suppose...

 

its more of a safe bet to run either Densos or NGKs based on Toyota recommendations, although I have run Bosch platinums in a 2.4l hi lux truck and they ran better than any others including NGK. my most recent trucks 3.4l and now 2.7l im running the Toyota rec'd Denso, they run better and are very cost effective, the 2.7l the plugs need not be changed till over 100k miles they are iridium long life denso.

 

well this is partly why I brought it up, it seems like a large portion of mechanics out there prefer to use autolites since just like you, I keep finding them "all the time" in jap cars

I mean, there must be "some" reason why they keep using them

as to running bad, I have never seen it to be due to the type of plug, just that it needed a plug changed so....

that said, as I mentioned in the first post our v6 need multi prong plugs so I can understand a single prong not lasting as long or working as good in them

im in no way suggestion autolites are better, just trying to figure out why some mechanics feel they are, or they must since that's all they keep putting in

 

while we are talking about plugs, has anyone formed any sort of opinion between ngk and denso if there is any difference in quality, performance, lifespan, and if one is a best choice over the other?

 

Maybe it's just availability. More likely to find autolite plugs at the parts stores? Who knows

 

I have to agree most garages get on the phone and say I need Yada Yada plugs wires for my Yugo .

Very seldom is brand ever mentioned you get the house brand .After all it is not going in my vehicle .

I am sure in different parts of the country different brands sell better

 

^head from my first tacoma. I bought it for next to nothing, thought it might have a blown head gasket but ended up being a cracked head.

Looks a lot like an electrode from a spark plug in a running engine don't it?