Car fuel additives - Do you use one?

[BigDataPro]

My Renault Kadjar (Diesel) is about 5 years old, done 20K+ miles. Regularly serviced and in fact recently came back from service too. Very frequently getting "Check Injection" and few other warning lights even after changing injector a year ago.

Having gone through various articles on the Internet, I have come to believe that Supermarket fuel might be a problem due to its inferior quality. Some seem to have got rid of these problem by using Fuel additives.

There seem to be a plethora of additive types like DPF cleaner, System Cleaner, Injector cleaner ... so on and so forth. Just wanted to ask if any one using it, is it worth it? Have you had any problem that has been resolved through use of these additives?

[Fraidycat]

One of our mercs, 5 years old has a 1.6 renault diesel init, its supposedly a Merc but not really because it has a renault engine

Mileage on it is 35,000 miles, never had problems putting regular BP fuel in it, BP being our nearest garage. Although given what you posted maybe i should switch to premium fuel instead of regular.

Sounds like you have a Lemon, i would sell or part exchange it.

Knew someone who had a intermittent check engine light on a BMW. Couldnt find any mechanic who could sucessfully diagnose the issue. They sold it to we-buy-any-car during a period when the warning light was off

[Paddy]

My Renault Kadjar (Diesel) is about 5 years old, done 20K+ miles. Regularly serviced and in fact recently came back from service too. Very frequently getting "Check Injection" and few other warning lights even after changing injector a year ago.

Having gone through various articles on the Internet, I have come to believe that Supermarket fuel might be a problem due to its inferior quality. Some seem to have got rid of these problem by using Fuel additives.

There seem to be plethora of additive types like DPF cleaner, System Cleaner, Injector cleaner ... so on and so forth. Just wanted to ask if any one using it, is it worth it? Have you had any problem that has been resolved through use of these additives?

I write with a great deal of experience on the subject.
You don't need additives. Additives are no better than snake oil and that includes DPF Cleaner.

There should be no need to change an injector on a five year old vehicle; in fact by doing so may f**K it up if not done correctly eg by a garage who is out to make money or just plain stupid. Injectors usually need to be coadded and programmed. Just replacing an injector will cause loads of other problems.

Firstly buy a good diag tool and use it! I recommend this one, I have used it on Citroen, Peugeot, Renault and Mercedes
https://www.ebay.co.uk/itm/331489667...MAAOSw1HxZ09VY

If you need to run tests, you will need a much more expensive one, but this one is fine for ditags and resetting codes.

1. Injector Problems are usually injector seal problems that need the copper washers replaced. Check to see if there are any soot deposits around the injectors. This is a DIY job costing about £10 or £300-£500 by a garage. When the injectors are out, you can then clean them with a de-coke cleaner and WD40. When the copper washers leak, (they all do at some time) the compression drops and the fuel does not burn correctly causing black smoke which in turn fills up the DPF and CAT. It also cokes up the depollution system. No amount of snake oil will fix it!

2. Your DPF will clean itself when you take a run on the motorway (engine at normal temp + 3500 rpm for 5 mins. Your scan tool will tell you when it was last done (under DPF info should read 0 to 5% soot last run XXXkm) If it's not working, its because of too much soot in too shorter time caused by 1 above.

3. The only time your DPF will need cleaning is when it gets too much ash inside (not soot). This happens when it gets old (eg over 150,000 mls. It can be cleaned with drain cleaner. (five bottles at Poundland will do it), then flush with water, dry it and refit.

4. Keep an eye on fuel consumption, this is the first indicator that something is up.

You are welcome to come back after doing a scan

[AtW]

Use Premium fuels like BP Ultimate - for diesel it improved range for me, making it actually cost efficient buy. Expect at least 3 full tanks before any difference is visible.

[Paddy]

One of our mercs, 5 years old has a 1.6 renault diesel init, its supposedly a Merc but not really because it has a renault engine

Mileage on it is 35,000 miles, never had problems putting regular BP fuel in it, BP being our nearest garage. Although given what you posted maybe i should switch to premium fuel instead of regular.

Sounds like you have a Lemon, i would sell or part exchange it.

The same 1.6 is used by Merc and BMW and Renault, Volvo Mazda et all. The problems are caused by poor maintenance mainly by garages. The engine is very strong and will last 300,000+ miles but the depollution side needs a lot of proper maintenance.

[BigDataPro]

I write with a great deal of experience on the subject.
...

Wow. You seem to have a fantastic knowledge about cars and their inner workings (at least compared to me!). Thank you.

I have a cheaper version of OBD-II tool that I have used intermittently to clear off the errors. Having said that, I spoke to Renault dealer who said there will be a diagnostic charge of £99. I will be taking it to my local mechanic to look at the Injector seals. I'm afraid I'm not confident enough to do it myself.

[Paddy]

Wow. You seem to have a fantastic knowledge about cars and their inner workings (at least compared to me!). Thank you.

I have a cheaper version of OBD-II tool that I have used intermittently to clear off the errors. Having said that, I spoke to Renault dealer who said there will be a diagnostic charge of £99. I will be taking it to my local mechanic to look at the Injector seals. I'm afraid I'm not confident enough to do it myself.

£99 is a rip-off. I lost trust in my Renault garage when the service sheet had ticked boxes for topping up the automatic transmission fluid when the car was a manual. Their excuse was the mechanic fills in the for after the service is complete.
When you run a diag, what pops up as an error may not be the source of the problem. The advanced diagnostics that run off a tablet or laptop will run tests on the components. But the trouble with most garages, the will keep swapping out parts until eventually the right part is swapped. However, sometimes a problem can be as simple as as faulty plug on a sensor.

Your local garage may do a compression test to check, but most often it's the seals. Ideally, injection seals in a Diesel should be part of a long service but the manufactures would not like to promote that.

[Scorp1]

I've always tried to use Shell. I find it runs better. But as for additives I would only run it with that on a full tank to the brim !

[vetran]

OBDII tool for a tenner is what I use.

The Ford Mondeos have an issue with EGR valves as they get older. Every year the emissions tests are squeaky bum time. Every MOT I was revving the bits off it for 20 minutes to pass the emissions tests. Now a couple of weeks before the MOT I pop a couple of bottles of redex through the petrol tank. Now it sails through without a care. EGR valve failures are rare.

£4 to pass an MOT seems cheap to me.

[anonymouse]

Lots of these type of questions in the car forum "I bought a car that's done 2,000 mile in 12 months, owned by Miss Daisy. What can I do". Usual answer is bottle of Redex/STP and an Italian Tuneup. Saab TTID especially don't like short journeys, just clogs up the DPF, then there's the EGR, plus the swirl bars. Don't get these problems with a petrol engine.