Different brands of spark plugs installed
- Thread starter Tundragod
- Start date
Toyota does it at the factory.
Yep. Our fj had Denso on one side and ngk on the other. That's how it was built.
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- Nov 28, 2021
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Ahh, the old 75% off trick got you!
The other day I went to petsmart to get the special dog food that our dog likes. I saw some bags with 50% off stickers on them. I grabbed one and started walking up front, then I thought about it and put it back and grabbed the full price one instead.
The reason we buy this special dog food is because our dog has stomach issues and throws up often . The 50% off bag was about 2 weeks from being expired, the full price ones were good for almost a year.
Would it have made a difference to our dog, I don't know, but I decided I didn't want to take the chance, so I chose to pay more.
I don't have OCD, but personally having 2 different spark plugs might bug me.
A couple of years ago I bought a set of Michelins and noticed that one had a different manufacturer date and was made in a different country than the rest.
I decided to keep it, but it does bug me when I think about it. Does it make any difference, I don't know.
Please pull those plugs in 100,000 miles and post the pictures!
The other day I went to petsmart to get the special dog food that our dog likes. I saw some bags with 50% off stickers on them. I grabbed one and started walking up front, then I thought about it and put it back and grabbed the full price one instead.
The reason we buy this special dog food is because our dog has stomach issues and throws up often . The 50% off bag was about 2 weeks from being expired, the full price ones were good for almost a year.
Would it have made a difference to our dog, I don't know, but I decided I didn't want to take the chance, so I chose to pay more.
I don't have OCD, but personally having 2 different spark plugs might bug me.
A couple of years ago I bought a set of Michelins and noticed that one had a different manufacturer date and was made in a different country than the rest.
I decided to keep it, but it does bug me when I think about it. Does it make any difference, I don't know.
Please pull those plugs in 100,000 miles and post the pictures!
I hear ya. The guy at AAP said, "don't mix". I was neither agree nor disagree so I bought them. The "bug me" made me started this thread.
100k miles? I only put on <3k miles/yr in the last 5 years since I bought it. I won't have this car 33 years from now. I hope I'll be alive in 33 years, lol.
Anyway, I bought the car with 135k miles. Previous owner said timing belt was done at 115k miles (2018) but I don't know if spark plugs was replaced or not. They didn't look worn when I inspected them in 2021. It is now 149k miles. I bought those plugs thinking that in 7 years from 2018, I may do the timing belt and replace the spark plugs then. Wait, that's next year already. Time flies.
100k miles? I only put on <3k miles/yr in the last 5 years since I bought it. I won't have this car 33 years from now. I hope I'll be alive in 33 years, lol.
Anyway, I bought the car with 135k miles. Previous owner said timing belt was done at 115k miles (2018) but I don't know if spark plugs was replaced or not. They didn't look worn when I inspected them in 2021. It is now 149k miles. I bought those plugs thinking that in 7 years from 2018, I may do the timing belt and replace the spark plugs then. Wait, that's next year already. Time flies.
If the car is running like normal, I would keep the plugs you got in there.
Has anyone ever figured why Toyota does this?
It's not like they are doing it for a specific reason, it's just how the assembly line and parts availability worked out. Most likely they have one person on each side of the line installing plugs and they each have their own spark plug supply which gets filled with whatever the last shipment was.
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I don’t think it’s for reason, I think it’s just what they have on hand, most automaker want their cars to run top-notch just like the military, but it all comes down to what is available and usually the cheapest price
Former Toyota Master Tech.
I was told by a factory rep that Toyota did this on engines with separate cylinder banks V6, V8 etc, as a way of equitably satisfying their parts suppliers.
Heck, when we were poor teens in the 70's, we likely had 8 different plugs in our muscle cars 
So, my wifes Aunt had a V6 Hyundai Santa Fe (3.3L I believe.) Visiting us from Massachusettes a couple years ago. I think her car was a 2015 or a 2016. She had around 100K on it, so I told her I would do the 100K maintenance on it. Drain / Flush of Transmission fluid, Coolant, oil/filter, air filter, cabin filter, plus her spark plugs. I had only bought 4 plugs, when I should have gotten 6. I had bought Denso, which is what her car came with. The parts store only had the NGK's. So, she got 2 NGK's.......
Car ran fine. She drove back to Mass. and still running them to this day. If I remember right, I did her rear brakes also. Forget what I even used.
Car ran fine. She drove back to Mass. and still running them to this day. If I remember right, I did her rear brakes also. Forget what I even used.
No issues doing this, but it would bug the heck out of me so I wouldn't. If it were me I would've bought the 4 NGKs on sale and ordered 2 more online, even if full price. Still saving you money.
I was told that the heads were manufactured at 2 different plants,they stick plugs in them at the factory and use the closest supplier.
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BMW explicitly forbids mixing spark plugs:
SIB120105 from Dec 2010: https://charm.li/BMW/2009/328i Seda... - Iridium Spark Plug Info/Application Chart/
SIB120105 from Dec 2010: https://charm.li/BMW/2009/328i Seda... - Iridium Spark Plug Info/Application Chart/
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