A VW Crafter With an Oil Filter Blocked Solid: Simon, Fallsbrook Motors, Streatham

At Fallsbrook Motors, Simon brought up a photo on the office computer to show us. It showed an oil filter from a VW Crafter that had come in the week before: a lease van, around 80,000 miles on it, and a filter coated in thick black sludge. "Completely, completely all gunged up," was how he put it, "and obviously not doing its job. We thought it would be bye bye to the engine."

So far, it hasn't come to that. The van got a new filter, two cans of flush with some flushing oil, a good twenty to thirty minutes of running, then fresh oil and another new filter. "And it's gone out, and all seems to be all right."

Simon runs Fallsbrook Motors, on Fallsbrook Road in Streatham, south London, and took it over in 2019. We filmed with him on 7 November 2025.

Watch the video with the full transcript

A garage on Fallsbrook Road since about 1952

"We think it sort of started in 1952, by the Bate family," Simon says. "Been a garage on this site all of that time." The history is on the walls of the office. There are black and white photographs of the site, including the rented lock-up garages it used to be and a set of garage doors lettered for tyres, oils and accessories, and there is an old framed business registration certificate.

In one of them there is a steam train going past. The railway still runs along the back of the site, a short walk from Streatham Common station, and in the old picture the smoke from the engine hangs over what looks almost like open country. Standing in the workshop today, with its MOT bay and cars up on the lifts, it takes a moment to see it as the same place.

"It went through three generations of the Bate family, and I took it over in 2019. So, well, over 70 years of being here as a garage. A long time."

A Ford apprentice who never stopped using it

Simon's history with TEC 2000 is older than his time in charge of the garage. "I've been using TEC 2000 products since I was an apprentice, so started using them in approximately 2001, 2002, when I worked at a Ford main dealer." That makes it close to twenty-five years with the same cans, across a dealership workshop and his own.

An add-on to every service

Every service customer at Fallsbrook gets asked.

The offer is spelled out on a sign at the garage: "Add some TLC to your vehicle service with TEC 2000. Buy 1x engine flush and 1x fuel additive for £26. Usual price £32. Recommended with every service." It is a straightforward way to do it. The customer sees the price, sees what it is for and decides.

"We thought it would be bye bye to the engine."

Simon, Fallsbrook Motors

Customers who flush every year

Simon sees the difference when he opens engines up.

He says the same about the fuel side: "Fuel system cleaners, again, with customers that do use them, we notice we get a lot less injector problems, fuel pump problems. Customers also report an increase in miles per gallon as well." That last part comes from his customers' own experience, and Simon passes it on as that.

Why the oil drains faster

Simon sees the same thing at the drain plug every time.

By "dilutes" he means the flush thins the old oil before it is drained. Old oil is thick with what it has picked up: soot, sludge, oxidised oil. Warm it up with a flush in it and it runs out of the sump faster and more completely, and less of it stays behind in the galleries and the corners of the sump to mix with the new oil. Sean at Turner Automotive in Twickenham describes the same thing from forty years of oil changes: with the flush in, "it becomes looser, more fluid coming out." It is also the other half of the story Dave at Banstead Road Garage told us, about a customer who didn't believe his oil had been changed because it looked so clean.

Simon also recommends it after an engine replacement. "If we put a new engine in, a car would normally come back after 1,000 miles. We'd always recommend flushing it then and at every service interval." The first oil in a new or rebuilt engine picks up assembly debris and running-in particles, and getting that out properly at the first check-up is cheap insurance on an expensive job.

The Crafter with the blocked filter

Here is the van from the top of this page, in Simon's words.

Looking at what came out of it, Simon's guess at the van's history was blunt: "I reckon it might only have had one oil change in that time." If he is right, that is one oil change in around 80,000 miles, which is how a filter gets into that state.

What a blocked oil filter means for the engine

A filter that full doesn't stop oil reaching the engine. Every engine has a filter bypass valve, in the filter itself on spin-on types or in the housing on cartridge filters like this one. When the element blocks, the valve opens so the engine keeps getting oil rather than starving. The catch is that the oil going round is now completely unfiltered. By the time a filter looks like this one, the engine has been running on dirty oil for a long time, and the sludge that blocked the filter is very likely sitting in the sump, the pick-up strainer and the galleries as well.

A plain oil and filter change would not have dealt with that. Fitting a new filter first meant the engine had a working filter while the flush did its job. Two cans, plus flushing oil, because of the state it was in. Simon ran it for "a good 20, 30 minutes", his own timing for an engine in that condition. Then everything out, and a second new filter to catch whatever the flush had loosened.

He was careful about the result. "All seems to be all right" is a mechanic's way of saying the van went back to work instead of waiting for a new engine. When we spoke to him, about a week later, that was still the case. For a lease van, that was the outcome that mattered.

Diesel emissions: filters first, then the flushes

Asked what he does when a diesel comes in with high emissions, Simon didn't start with chemistry.

A diesel MOT emissions test measures smoke, not gases: the tester revs the engine hard several times and a meter reads how opaque the exhaust is. A choked air filter or dirty injectors will push that reading up, and a fresh fuel filter keeps clean fuel reaching the injection system at full pressure. Simon's package deals with the obvious restrictions first, and the flushes go in alongside the new parts. "Normally" is his word for how often that is enough.

Four cars of his own, all on TEC 2000

Simon's own car was standing in the workshop: a black 1968 Jaguar 420. It hasn't been rebuilt. "It was off the road for many, many years, so I've been recommissioning it over the last few years." It is one of four.

His classics always get Oil Booster. "All of my classic cars will always have an Oil Booster 'cause obviously seals, rubber seals, they start to crack and whatnot in the classic cars." He uses it the same way on customers' cars with big mileages: "We use that in the more high mileage and older cars. Just helps with condition of seals and things like that, hopefully to stop oil burning, or certainly reduce that."

Old rubber is the weak point of any car that has spent years standing. Seals that sat dry and cold for a decade harden and shrink, and once the engine is running again they are where the oil starts to find its way out, or in. A mechanic who owns four cars and runs TEC 2000 in all of them has already made up his mind about it.

The products Simon uses

• TEC 2000 Engine Flush. Offered with every service, every year. Recommended at 1,000 miles after a new engine.
• TEC 2000 Diesel System Cleaner and TEC 2000 Fuel System Cleaner. The fuel additive in the service offer. Simon talks about fuel system cleaners without naming which one.
• TEC 2000 Oil Booster. In his own classic cars, and in customers' high-mileage and older engines.

Questions we get about this

What happens when an oil filter gets blocked?

The filter bypass valve, in the filter itself or in its housing, opens and the engine carries on running on unfiltered oil. It won't starve straight away, but everything the filter should have caught goes round the engine instead. A filter in that state is a sign the oil hasn't been changed for far too long, and the sump and galleries need cleaning, not just the filter changing.

Can a heavily sludged engine be flushed?

The Crafter at Fallsbrook was a worst case. What Simon did there was a new filter first, two cans in with some flushing oil and a good 20 to 30 minutes of running, then a full drain, fresh oil and a second new filter, and when we filmed, the van had gone back out and all seemed to be all right. Follow the product instructions for the dose and time, and on a very neglected engine check the oil pressure and the filter again after a few hundred miles.

How often should an engine be flushed?

At Fallsbrook Motors it is offered with every service, and customers who take it once a year are the ones whose engines Simon finds clean inside years later. After a new engine goes in, he recommends a flush at the 1,000-mile check and then at every service.

More from the same trip

This film was shot on 7 November 2025, on a two-day trip round garages in south London and Surrey. Dave at Banstead Road Garage had a customer who didn't believe his oil had been changed, and Ricky at The Test Station a wet-belt Peugeot with an oil problem other garages hadn't sorted. Joe at Joe's Repair Shop in Epsom talks about five years of TEC 2000 in every service.