The Customer Who Couldn't See the Oil on the Dipstick: Sean, Turner Automotive

A customer walked out to their car on the forecourt after an oil change and pulled the dipstick. They couldn't see any oil on it. So they came back in and told Sean he hadn't put any oil back in the car. Sean had to go out with them and show them, with a piece of tissue, that there was oil in the engine. The oil was there. It was just so clear that the customer hadn't been able to see it.

Sean has worked with cars for forty years, and he started at Ferrari. We filmed with him in July 2024 at The Green, Turner Automotive's branch on Colne Road in Twickenham, with David from TEC 2000 UK asking most of the questions.

Watch the video with the full transcript

From Ferrari to Twickenham

He is precise about the forty years: "I've been working with cars now 40 years. Yeah, 40 years exactly this year, in fact." When David asks where it started, the answer surprises him: "Believe it or not, I started off at Ferrari, literally." David: "Really?" Sean: "So I was trained, trained Ferrari for the first sort of 10, 15 years of my career."

After that he went travelling for a couple of years and, in his words, "fell into the sort of the customer services side of this industry. But I still actually fix cars, as I am now." Today that is at The Green, the Turner Automotive branch on Colne Road in Twickenham that looks after VW and Audi group cars and runs an MOT bay. The lettering on the window behind his desk says it plainly: independent VW and Audi group specialists.

That mix is worth noticing. Sean works on the customer side of the business, and he still has his hands in engines. When he says a product works, he is talking about what he sees at the drain plug, and when he talks about selling it, he is talking about his own customers across his own desk.

"You know it's done its job"

TEC 2000 came into his working life "around about 10, 11 years ago, maybe 12 years ago", and the product that convinced him first was the Engine Flush, "the green one there" on the desk in front of him.

In a British garage "engineer" usually just means the person working on the car, and what Sean describes is what any mechanic can see at the sump plug. Old oil that has done its miles comes out slow and heavy. With a flush in it, it runs. Simon at Fallsbrook Motors in Streatham sees the same at the drain: the oil comes out a lot quicker, and more of it comes out.

"You've got to put clean oil into a clean engine, and there's your answer."

Sean, Turner Automotive

Clean oil into a clean engine

When David asks why he recommends these products on every service, Sean reaches for the simplest comparison he can find.

At Turner Automotive the flush goes into every service, and Sean tells the customer before he does it. "I'm upfront with the customer, tell them that I'm gonna put one of these in. There is benefits to it." His explanation to them is the same one he gave us: "The fresh oil will go in and stay cleaner longer if you pull out all the rubbish prior to." He singles out diesels, "because diesel cars, as we know, they're dirty."

The TEC 2000 Engine Flush goes into the warm engine's old oil, one 375 ml can for every 4 to 5 litres, and the engine idles on it for about fifteen minutes before everything is drained with the old filter.

A diesel that failed on smoke

The fuel side is where Sean says he has been most impressed, "particularly the diesel cleaner". On the day we filmed, the example was parked a few metres away.

When we filmed, that car was still waiting to be collected, so its retest is Sean's forecast rather than a result. He makes it with confidence because he has seen the same thing many times. The routine is the part worth copying: Diesel System Cleaner in the tank, and a proper run at motorway speed before the car goes back on the smoke meter. A diesel's MOT emissions test measures how opaque the exhaust is under hard revving. A car that only does short trips often turns up with a sooty exhaust, and a long run at speed gives the treated fuel time to work before the retest.

The old Volvo that flew through

When David asked for other examples, Sean went back to a car that had worried him.

David suggested the Volvo had had all three products. Sean began to agree, then corrected himself: it was two, the Engine Flush with the oil change and the diesel additive in the tank. No Oil Booster on that one.

Oil Booster on BMWs that burn oil

Oil Booster has had its place at Turner Automotive too, on a smaller number of cars.

His summary of the whole range, before he moved on: "Throughout the range of products, yeah, absolute glowing results all around." TEC 2000 Oil Booster goes into fresh oil after the service.

Only when the car needs it

Sean's approach to selling the fuel additives is the most useful thing he said for any garage owner.

Then he adds the detail that makes the rest of it credible.

"And in a lot of instances it is necessary," he says. For his own petrol car that means Fuel System Cleaner, which he calls a "fuel tank additive". A can a month is Sean's own routine, and it says more about what he thinks of the product than anything he could tell a customer.

The customer who couldn't see the oil

Before the interview properly started, David asked whether customers ever give feedback. Sean's first answer was "No", then "only on maybe, maybe on the additives", because the additives are "something they really, really, really see". The flush is different: "once we put the new oil in it, you know what customers are like. They just see the oil." Which brings us back to the forecourt.

"So I've had it from one spectrum to the other spectrum," he says: customers who ask whether their oil was changed at all, particularly on diesels, and one who thought none had gone back in because it was too clear to see. David laughed and said he had heard the story a few times. We have too. Dave at Banstead Road Garage in Carshalton had a customer accuse him of not changing the oil for the same reason, and settled it with the CCTV footage.

For anyone checking their own car: fresh oil is amber and thin, and on a clean dipstick in daylight it can be almost invisible. Laying the dipstick flat on white tissue or kitchen roll leaves a mark that shows the level and the colour at the same time.

The products Sean uses

• TEC 2000 Engine Flush, "the green one". In every service at Turner Automotive, and on the old Volvo.
• TEC 2000 Diesel System Cleaner. For diesels that fail the MOT on smoke, followed by a motorway run.
• TEC 2000 Fuel System Cleaner. For petrol cars that need it, and in Sean's own car about once a month.
• TEC 2000 Oil Booster. On one or two BMWs that were burning oil.

Questions drivers ask about this

My diesel failed the MOT on smoke. Will a fuel additive get it through?

If the cause is deposits rather than a mechanical fault, it often can. Sean's routine is Diesel System Cleaner in the tank and a good motorway run before the retest. The very old Volvo he told us about, a customer's car, also had the Engine Flush with its oil change and went from "massively over the top" to passing. A diesel with a failed injector, a stuck EGR valve or a damaged DPF needs those faults fixing first.

Why does my oil look like there is none on the dipstick?

Because fresh oil is light and thin, and on a clean dipstick in daylight it can be very hard to see. Lay the dipstick flat on white tissue and the mark shows where the level is. If the level is right, the oil is there.

Does an engine flush make the new oil stay clean for longer?

That is what Sean tells his customers, particularly about diesels: "the fresh oil will go in and stay cleaner longer if you pull out all the rubbish prior to." The flush takes out more of the old oil and the deposits that would otherwise darken the new charge.

More from our garage visits

Dave at Banstead Road Garage had a customer who didn't believe his oil had been changed, Ricky at The Test Station a wet-belt Peugeot with an oil problem other garages hadn't sorted, and Simon at Fallsbrook Motors a VW Crafter whose oil filter came out blocked solid. Charles Ivey Specialist Cars in Surbiton look after Porsches, from 1960s classics to modern diesels.