I have a 93 Corolla that I think could probably use new spark plugs and a tune up. I say this because according to the records it got new plugs at 30k miles, and then again at 55k miles. It’s currently at 88k miles.
Which spark plugs should I use? Should they be OEM? I hear that many platinum plugs will last 100k miles. Should I be using those instead?
You should use what the factory recommends and while you don’t have to change the plugs every 25k miles, in most cases, I would never allow plugs to remain in place for a 100k miles.
Even with platinum plugs subtle misfires may develop long before a 100k miles and allowing the plugs to remain in place that long may cause the plugs to seize in the cylinder head. This means when removed the next time they may strip out or damage the threads and it’s going to cost considerably more to fix this problem.
That car came new with plugs that said Toyota on them but they looked just like Denso plugs, with the distinctive ‘U’ shaped profile on the ground terminal. They worked just fine and you can get the comparable plugs now very inexpensively. They will last at least 20k miles and still look and work like new. That’s four years at the rate you are driving. How do the cap, rotor and wires look? They will get old and start cracking at some point.
Use Permatex Anti-sieze on the threads. Prevents the gaulling that you describe. Even copper-plus will seize in the heads at 12K miles. After having to get the spark plug holes heli-coiled in my VW back in college in the 80’s because of seized plugs that ripped out the threads, I’ve been using it ever since, and have had zero problems with seizing with all my cars and truck since, even my long-lasting Toyota Pick-up that lasted 325,000 miles on a steady diet of copper pluses (NGK) every 12K or my Explorer that is on it’s third set of FoMoCo platinums at 169,000.
A basic copper core plug will be fine for this car. Grab a set of Autolite plugs at Walmart.
Denso and NGK both make OEM plugs with the U-groove that this car uses. Look in your owners manual and it will tell you both options (and the model numbers). Go to your local auto parts store and you can pick up either brand for less than two bucks each. DON’T use Autolite plugs in your Corolla. You will save very little money and your car will not run as well.
I agree. On Japanese cars, I would only use Nippon Denso or NGK spark plugs, of exactly the same model number specified in the Owner’s Manual. Anything else will not yield results as good as those two brands.
I take care of a family members 93 Geo Prizm that still runs like clock work. The last tune up I used Autolite plugs with excellent results, but seeing how Denso U-grove are OEM and don’t cost that much more I will probably use them next time. I stand corrected.
NGK’s BKR5EYA spark plugs at 0.031-0.032 inch gap.
You do not need Platinum or Iridium. I had Bosch Platinum+4 plugs on my 94 Prizm and they caused terrible gas mileage.
Get the stock, keep your money in your pocket.
Either NGK or Denso, no other brand, no other gap.