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I was today years old when I discovered that Esso once sold spark plugs.
We’ve been working on our 1956 Ford Popular and, after removing the four plugs from its little sidevalve engine, something caught our eye.
ESSO.
Printed clearly around the white ceramic insulators.
We’re used to seeing names such as Champion, Lodge, KLG, Bosch and NGK on old spark plugs.
Esso?
That was a new one on us.
And once we started looking into them, they turned out to be far more interesting than four rusty old plugs have any right to be.
Search for Esso spark plugs today and you’ll discover that they weren’t some obscure one-off promotional item.
Period Esso-branded spark plugs survive in a variety of types, and unused new-old-stock examples still occasionally appear for sale.
If you fancy seeing what’s currently lurking on eBay, have a rummage through the Esso spark plugs currently for sale here:
https://go.ukbarnfinds.com/essoplugs
But there’s an interesting distinction to make.
Although they carry the famous Esso name, specialist vintage spark-plug sources indicate that Esso-branded plugs were made by KLG.
That makes considerably more sense.
KLG was one of the great British spark-plug names.
The company grew from the work of racing driver Kenelm Lee Guinness, who became closely associated with the development of KLG spark plugs in the early days of motoring.
By the middle of the 20th century, KLG was a major British manufacturer, supplying spark plugs for both automotive and aviation use.
That wider reputation is well documented. Period Rolls-Royce records, for example, include correspondence and testing involving KLG spark plugs, showing just how established the company was as an engineering supplier long before our Ford Popular was built.
Specialist vintage spark-plug references also state that Esso plugs were made by KLG.
So describing these as Esso spark plugs is absolutely correct from a branding point of view.
But the manufacturing expertise behind them appears to have come from KLG.
These particular four plugs came from our 1956 Ford Popular 103E.
That’s the wonderfully basic little Ford powered by the familiar 1,172cc sidevalve four-cylinder engine.
And now we know exactly what we’ve got.
The plugs are clearly marked:
ESSO Z-42
on their ceramic bodies.
We haven’t found a reliable period Esso application chart that definitively tells us where the Z-42 sat in Esso’s range or what its direct modern equivalent would be, so we’re not going to invent an answer.
What we can say with certainty is that four Esso Z-42 spark plugs were fitted to this particular Ford Popular when we acquired it.
Current specialist parts suppliers list a 14mm spark plug equivalent to the old Champion L10 specification for the Ford Popular 103E, with Champion L86C commonly sold today as the replacement equivalent.
That gives us useful context, but it doesn’t automatically prove that the Esso Z-42 was Esso’s original catalogue equivalent.
It actually makes perfect sense when you think about the motor trade of the period.
Esso wasn’t simply somewhere motorists bought petrol.
Service stations were part of a much wider motoring world where drivers bought fuel, oil and all sorts of consumables needed to keep a car going.
Spark plugs fitted neatly into that ecosystem.
And Esso certainly understood ignition and combustion technology.
Its research operation was involved in technical work around fuel behaviour, combustion and spark-plug fouling during this era.
So while the plugs themselves appear to have been manufactured by KLG, the Esso name on a spark plug was hardly random.
It was another way of keeping the brand under the bonnet as well as on the petrol pump.
Nobody is going to mistake our set for new old stock.
The steel bodies have developed substantial surface corrosion and the ceramics carry plenty of grime and staining.
And that’s exactly how we like finding things.
These haven’t spent decades sitting untouched in a cardboard box.
They’ve been screwed into an old Ford engine and used for the job they were made to do.
Quite when they were fitted is another question entirely.
They may have been installed decades after the car was built.
Without dated paperwork tying them to a particular service, anything more precise would be guesswork.
But they’re staying with us.
This was another thing that surprised us.
Old spark plugs aren’t necessarily worthless workshop rubbish.
Collectors look for unusual brands, early designs, display plugs, boxed new-old-stock examples and plugs associated with famous manufacturers or fuel companies.
That collecting world overlaps neatly with petroliana and automobilia.
Esso is already one of the most recognisable names in petrol-station memorabilia, so combine that branding with an unusual period automotive component and you suddenly have something much more interesting than an ordinary used service part.
We’ve seen Esso spark plugs advertised for surprisingly strong money, particularly where they are unused, boxed or of an unusual type.
Values vary enormously, of course.
Condition, rarity, exact type, packaging and whether you’re looking at one used plug or a complete unused set can all make a big difference.
So we certainly wouldn’t suggest that four rusty plugs like ours automatically represent buried treasure.
But before throwing old branded spark plugs in the scrap bin, it’s worth having a proper look.
And this is exactly the sort of thing eBay is brilliant for.
Search for one obscure old motoring item and twenty minutes later you’re looking at spark plugs you’ve never heard of, old garage displays, petrol cans and boxes of new-old-stock components that have somehow survived untouched for half a century.
For a broader rummage, have a look at the vintage Esso spark plugs currently on eBay:
https://go.ukbarnfinds.com/essoplug
You can also try searching specifically for:
Esso Z-42 spark plug
or
Esso Z42 spark plug
because sellers don’t always use the hyphen consistently.
Just don’t blame us if you emerge half an hour later having bought an old Esso oil can as well.
This is exactly why we enjoy going through cars that have been sitting for years.
The big story might be the car itself.
But often it’s the little things that keep us interested.
An old dealer sticker.
A period accessory.
Something hidden under a seat.
An ancient tool in the boot.
Or, in this case, four rusty Esso Z-42 spark plugs carrying a petrol-company name we didn’t even realise had appeared on spark plugs.
Our Ford Popular has already produced a few surprises.
We suspect it isn’t finished yet.
We’re always interested in old cars, motorcycles and the things that accumulate around them.
If you’ve got a classic vehicle you’re thinking of selling, or you’re clearing an old garage, shed or workshop containing parts, new old stock, tools, petroliana, signs, literature or motoring memorabilia, we’d be interested to see what you’ve got.
Things don’t need to be cleaned, sorted or individually identified.
A few photographs are usually enough to start with.
You can contact UK Barn Finds here:
https://ukbarnfinds.com/contact-us/
Sometimes the apparently insignificant things are the most interesting finds of all.
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