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What's the difference between NGK's "BCPR" and "BKR" Spark Plugs?

My owner’s manual says to use NGK BCPR5EY, which I’ve always used as replacement spark plugs and they seem to work ok. But I’m planning to replace the plugs and do a mini-tune-up this weekend, and the auto parts store tells me their computer says it should be NGK BKR5EY-11.

The parts stores seem to have changed they way they do things. It used to be that I’d just grab the plugs from the shelf, and if they didn’t have the # I was looking for, they’d have a cross reference to a different brand, like NGK to Motocraft or NGK to Bosch, etc. Now, when I ask them to check the cross reference to make sure these parts are compatible with my year/make/model, they don’t seem to have a way to check. All they have is what their computer tells them.

I’d like to use the plug the owner’s manual recommends. But the auto parts store can’t even tell me if they stock the NGK BCPR5EY. They can only tell by the code the computer spits out, which isn’t by that number. It’s by something like “6204”. That’s how they find it. Not by the NGK #. The guy said he’d have to go in the back stockroom and look at all the boxes of all the spark plugs to see if they had it, and he was to busy to do so.

Anybody else have this problem? Anybody know the difference between these two spark plugs? Are they interchangeable?

See if this helps.

Every number and letter on a spark plug has a significance.

Can I assume that the plugs are now pre-gapped and the addendum identifies the precise plug with the precise gap for the application? Considering the fragility of modern plugs I can support the effort to prevent plugs being damaged when widening the gaps. I recall AC doing the same thing 20 years ago.

Since you didn’t tell us the year, make or model I can only suggest you go to Rock Auto and see what they list for your car.

Amazon has your exact plug available. Total of 10 in stock. $2.43 each. Sounds like that particular plug is being phased out.

There’s also a listing for that plug at

I looked both plugs up on the NGK web site. It looks like NGK changed the way they designate the projected tip. Other than that, the two plugs seem identical.

Shelf space and shelf life…To make it more fun, NGK has changed their identifying system. No more markings like BCPR5EY. Now it’s just a four-digit number like 6204…

I have always been amazed that it takes a million different spark-plugs to do EXACTLY the same job…

“I have always been amazed that it takes a million different spark-plugs to do EXACTLY the same job…”

Back in the mid 1950s when I was in high school, my parents had a 1954 Buick, a 1952 Dodge, a LawnBoy 2 stroke lawnmower and a rototiller with a Lauson engine. The spark plugs all cross referenced to a Champion J-8, Now we have platinum tipped plugs, irradium tipped plugs, engines that require a different heat range plugs for different cylinders, etc. Give me a good old Champion J-8 or the equivaent AC 44 any day.

Thannks to all for comments. I was just wondering if there’s a reason the plug designation has been changed. Maybe somebody decided it needed a slightly different plug to pass newer emissions standards? It’s for a early 90’s Toyota Corolla.

Even in the old days, car manufacturers often changer the plug recommendation as the car aged.
In some cases they learned that the engines were either burning up or fouling plugs. If they were burning up plugs the went to the next colder plug, if fouling, one step hotter.
Your driving habits used to matter too, I usually went one colder.
These days the engine management systems are wonderful and plug recommendations are usually changed to simplify the number of plugs they have to carry.