Doctor Diesel, Features

Worried of Warminster

Letter 2

Dear Doc, I found the Diesel Car article (March 2013) on the used Jaguar X-Type 2.2 models very helpful.

I have owned a 2008 2.2 Sovereign estate six-speed manual for about 18 months. The car is a delight – responsive and refined – and I hope to keep it for many years to come.

For that reason, two issues that were picked up in the article concern me – the EGR valve, and the long term potential problems with the DPF. My EGR has already been replaced last month, under an after-market warranty with Warranty Direct, after 36,000 miles. However, this unit may fail again in another 30 to 40,000 miles.

Also, I keep reading long-term issues with DPFs, and I have two areas of concern. Are fuel additives, such as Millers Diesel Power Ecomax and Wynn’s DPF Cleaner, likely to prevent problems with either the EGR or the DPF?

I note the many adverts in Diesel Car for companies who will remove or bypass the EGR and DPF and then remap the electronics – your letters page is sponsored by Evolution Chips and the X-Type article mentions

Are the claims made by these firms borne out in practice? Is it legal to make these changes, and would the MOT be affected?

Would these be modifications in the eyes of my insurers, and also under the terms of my Warranty Direct warranty and need to be reported, with a possible increase in premiums?

I would appreciate your thoughts. Also, I read in the Daily Telegraph’s ‘Honest John’ column a reference to an in-depth report on DPFs by Diesel Car magazine; do you know how I can locate that please?


Adrian Bowden-Green

Good to hear from you. Your Jaguarrr seems to be really growling!

The DPF feature appeared in issue 299, July 2012, and can be ordered via our Subscriptions and Back Issue department by e-mail at or by calling 01926 339808. From it you should possibly glean a few tips to help preserve its life and reduce the frequency of regenerations.

I think that the legal position is mentioned in the feature. I wrote to the appropriate government department and they assured me that DPF removal, or tampering with any emissions systems, is illegal, but nobody seems to be enforcing the law.

Being illegal, if it came to the crunch, your insurance could also be invalidated, and it would certainly be a notifiable modification – and if they are well-informed, it would have to be rejected, being illegal!

What would be the point of all this legislation to clean up diesel emissions if anybody can simply deactivate the equipment?

Millers is good; regarding anything else, no comment, as I haven’t tested them all. The only problem might be ash content, and Millers checks out on this, and are totally aware of ash problems, as they manufacture special low ash engine oils themselves. I have not used DPF cleaners, and I would certainly not use them regularly and in normal circumstances.

If you get into problems with regeneration, they might be worth a try, and Wynn’s is a respected name. But do try all the handbook instructions regarding DPF regeneration first. It sounds like you were probably not the owner of your Sovereign Estate from new, and it could be that any previous owner did not treat it as it should have been – i.e. by giving the car reasonably frequent longish runs when the engine gets hot enough to regenerate the DPF properly, and fully.

If you care to set your OBC (on board computer) on current or instantaneous mpg, you will probably spot a regeneration when it is occurring, as the mpg will be noticeably low for the power demand, and the engine may feel a bit lumpy. It is also wise to keep a close check on oil level.

DPF problems can sometimes result in diesel fuel ending up in the sump, and thus give a rising oil level. That’s not good for lubrication, obviously. I don’t want to worry you about this, but it’s worth keeping an eye on. Hope that these few points help Adrian,

Doc Diesel

Reply from Adrian…

Letter 2_(1)

Many thanks indeed for your reply and for the excellent article on DPFs – more informative than anything else I have read.

Unsurprisingly, it has prompted a few further questions! You mention there are two types of DPF; is it likely that mine being basically a Mondeo engine is of the Eolys type? And if so, would that mean that, if in time it needs replacing, it would be in the lower price bracket?

I intend using a local garage for maintenance – because they are very good, local and less expensive than the nearest Jaguar dealership. Should I check they know the service mileage (where would that be stated?) for the Eolys renewal, and should I double check they are using the correct engine oil?

You mention that it is best to use branded fuel. Do you favour any particular brand or grade, such as V-power and Ultimate?

Finally, you suggest setting my OBC to current, but as far as I can see (unless you know different) my computer has only one mpg option, which is average. Is there another setting which is not obvious?

Best wishes,

Adrian Bowden-Green

No Eolys type fluid is used in your Mondeo type engine. It uses a catalyst-coated filter which is maintenance-free. I’m afraid that I can’t get any DPF prices, but Jaguar parts are rarely cheap!

But there will be a source of decent quality non-Jaguar DPFs, via your garage, and a DPF for a similarly engined Mondeo is only around £300 + VAT, plus a garage’s profit margin, of course.

Yes, do check that your garage is using a Jaguar-approved oil. Plain branded fuel is OK for me, but nearly always with Millers additive. Shell V-Power now seems to cost 8p/litre more than Shell Fuelsave, and BP Ultimate as much as 10 to 12p/litre more than cooking BP. That’s as much as 50p a gallon extra, which is twice as much as I used to pay for a full gallon of petrol when I was a lad, running a Morris Minor van. Absolutely scandalous!

I suggest that you consult your handbook regarding OBC computer displays. There usually is a current mpg display, but maybe your X-Type doesn’t have one. Also, you might like to read the recent ‘The Extra Mile’ in Issue 309 (April) which covered premium price fuels!

Cheers, Doc


I have a Honda CR-V 2.2 i-DTEC 2009, fitted with 17-inch wheels.

Although I like the CR-V in general terms, and it has proved inexpensive to run and maintain, it has always seemed to ride rather harshly and noisily on its Michelin Latitude Cross tyres.

Do you have any suggestions for alternative rubber that might give us a more comfortable ride when the tyres are to be replaced fairly shortly? What might be your thoughts regarding winter tyres, by the way?

Godfrey Hart

With the new tyre labelling regulations Godfrey, which give wet grip, fuel economy, and noise ratings for all new tyres, you do actually have such information available to draw your own conclusions – and I don’t mean that you need to go scouring the tyre depots, hunting around and looking at dozens of labels.

All these new ratings are posted on most of the online tyre supplier networks, like blackcircles, mytyres, kwikfit etc. But a bit of inside knowledge from me, I am sure, will not go amiss!

The current Michelin Latitude Cross tyres offer figures of F for fuel economy, C for wet grip, and have a 71dB noise rating. If you don’t actually traverse rough roads and boggy conditions, and only stay on fairly clean tarmac, then there’s the Michelin Latitude Tour, which is a more road-oriented Michelin tyre with ratings of C, C, and 69dB, although it’s not as quiet as the Goodyear EfficientGrip in that size, rated E, C, and 67db, but is a bit more fuel efficient.

Noise also tends to relate to ride harshness – both areas where Honda has always seemed to struggle a bit, and where Goodyear tyres help reduce road noise. I would definitely consider the Goodyears, and you should find that they are a good few pounds cheaper than the Michelins as well.

You ask about winter tyres, and it may be that your thoughts of ride harshness and noise are coloured by the long winter which we are suffering. Many parts of Britain have been subjected to long periods of near-freezing temperatures, day and night, and these are conditions in which winter tyres offer superior grip, but also offer a generally softer and quieter ride, although the latter depends also on tread pattern.

Winter tyres generally use higher proportions of natural rubbers, which harden less than most synthetic rubbers in cold weather, and I have read many reports of how quiet they run. I’m afraid that I don’t have specific experience or knowledge of winter tyres to offer any advice, but I would advise that you stick with major brands.

Many passenger car owners fitting winter tyres also buy a set of smaller diameter wheels, and fit higher profile winter tyres, but in the case of your Honda with its 225/65/17 tyres this is not relevant, and you can happily stick with your existing wheels, and just have the tyres changed twice a year.

With the way the weather has been recently, a change in November and April would seem about right!


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