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Local Citroen Dealer says they've shifted all models (inc XM) to 10,000 mile service intervals - including oil change. No doubt because of increased spec of oil etc.

I know lots of XM owners change their oil religiously at 6,000.

Talking to a BMW indy recently he recommends all BMW diesels use Mobil1 0W/40 Turbo Diesel (fully synthetic) and change at 15,000 miles. Expensive @ £34.00 for 4 litres - but read on!

Just spotted 200077228123 on eBay. It makes interesting reading (inc the 2 links).

I bet in reality the Mobil1 0W/40 Turbo Diesel is good for 18-24,000 miles! (Maybe the filters could still be changed at 6,000?)

Sampling / analysis at 6,000 miles anyone?

Comments / abuse / ridicule?

Hi Roy

Personally I dont believe in it. I am convinced that the longevity of diesels in particular is down to regular, frequent oil changes. I change mine every 5,000 and used the cheapest oil which has the required spec, at present £5.99 from Trago Mills.

I have always adhered to this policy and my previous XM had covered 292k when I sold it and was still going strong. My last CX had done 262k, over 150k of that by me.

However expensive the oil is, it still gets dirty.

Hi all,

I expect the main driver for manufacturers to extend the oil change interval is the pressure from the Government to reduce the environmental impact of their vehicles. I concur with Peter that the best way to achieve a long lived engine is frequent oil and filter changes.

Hi all.

Yes, firmly with Peter and Bigjohn on this with the diesels. Sensibly priced oil that meets the specs, frequently changed.
As an aside, a friend of mine has a V8 Beemer, in which he has religiously used Mobil Expensive (can't remember exactly which version, but £30 + a tin). Barely 100k miles --- tappet rattle. Also perceptible consumption.

Was talking to my indy recently about the longevity of the HDI compared to the old XUDs. He said they are tending to die quicker - and he is having to replace lots of turbos to keep them going. Something he never has to do on the older engines.

I have heard colegues say that they have read that the new generation of diesels are not lasting as long as petrols!

My indy puts it down to 2 things.

1) Oil change intervals. He is convinced that they still need 6,000 mile changes, and HDIs that have had it are giving him no problems at all and are capable of the expected 100s of thousand miles..

2) Supermarket fuel. He is convinced that when a car is running on supermarket diesel (esp for a long period) it has problems in the smoke test at MOT time, but most of his customers use branded fuel and never have smoke problems. He therefore assumes that it cannot be doing the engine good either.

2 is perhaps a bit more contreversial that 1. What do people think? I certainly avoid supermarket fuel as I remember years ago (when I was far too young to drive) someone putting supermarket petrol in their new high performance engine and having a very large garage bill for replacing filters, injectors etc due to very dirty fuel. He wasn't alone, and that has kind of stuck in my memory.
XM v6 sadist

The longer oil intervals are also dependent on what company car drivers find best. The majority of larger new cars are bought as company cars, do larger than average mileage and oil service interval becomes very important to the overall leasing costs. This drives the leasing companies etc... to demand longer intervals.

I completely agree though that if you intend to keep a car for many 10s of thousands of miles then frequent changes of oil are a very good idea. However it does depend on how the car is used. My Xm does about 5K miles a year and has an annual oil change - many short journey's etc. My Honda does about 25K miles a year and has 2 oil changes, however the Honda probably does exactly the same number of cold starts as the Xm, it's just the Honda ploughs up and down the motorway.

BTW you may notice the company that sells the highest percentage of it's cars as company cars is Vauxhall and they have 20-30K oil change intervals. Honda (very low percentage company cars) has 12K. When it comes to engineering I know which one I'd trust out of those two!



PS. Did anyone else read that Citroen came top (or maybe second) for European manufacturer in a poll of Warranty claims. It was a better performance than a lot of other brands. It kind of goes against many peoples thoughts of Citroen.
I cant say that I have ever had an issue with different fuels. I have driven about 1,000,000 miles in my driving life, using whatever fuel is available and have not noticed any difference. In the '50s there were all sorts of different fuels and grades available, Cleveland did an 'alchohol' petrol and there were various others and octane ratings from 92 to 100, they were the only important ones to observe as petrol engines had compression ratios from about 6-1 to 10-1.

I had my first diesel in about 1960 and only problem with that was that it 'set' in the very cold weather and there were no fuel heaters in those days. Warming the system up with a blowlamp was the way forward, or a pile of oily rags as used by lorry drivers! It probably wouldn't be a problem now as down here in the Westcountry it rarely drops below freezing, but we lived in Kent then, and the winters were colder!

Hi All

An interesting thread! I would not go along with extending the mileage between changes and consider the filter change to be just as important as the oil change. If an engine has done less than 120k then I use a better quality oil. I also keep an eye on the running temperature of the engine as running hot degrades the oil faster.


What I do notice about supermarket fuel - on the odd occasion I have had to use it (due to the regular fuel shortage there seems to be in Horsham) I get 70 - 100 miles less out of a tank given the same driving style (or perhaps even driving slightly more economically cos it is going down faster). I do tend to have a fairly heavy right foot - it may be different with a lighter touch.

At that rate it works out more expensive (even if it is a penny or so cheeper to start with).

Something else people are passionate about then!

We all have our own thoughts on it and are suitably convinced based on experience / recommendation and so on. The reason I thought the eBay post (and the related links) were so interesting was for the first time (as far as I'm concerned) there's an opportunity to explore the reality based on hard evidence.

It seems to me that the 6,000 mile oil change interval has been around for 40-50 years? Yet during that time there have (presumably) been significant technological advances in motor oils and there have certainly been major advances in engine technology - yet we still believe the oil needs changed every 6,000 miles - why?

I'm happy to be convinced that this is the case - I just don't trust the reasons we're given (from the Motor Trade / Oil Manufacturers). Where's the evidence? [After all - it's only a few years ago that European Legislation put a stop to the Manufacturers insisting that vehicles HAD to be serviced through their dealerships in order for the warranty to remain valid. So they're not renowned for acting in the best interest of the consumer in these matters.]

Coincidentally?? - service intervals seem to have shot up around the same time - why? Is it that the oils are now better - or the engines - or both? How much of it is to do with pressure from Government / Fleet Owners / Companies - and how much based on what's best for the car? Is this something the manufacturers are now using as a key selling point - and are they stretching the boundaries beyond reason? Have the manufacturers / dealers gone back to revise the recommendations for older cars?


I think your point about buying the cheapest oil available that meets the spec is very valid. I agree equally that however expensive the oil is - it still gets dirty (visibly within 50 miles in my experience). The purpose of the analysis is to monitor exactly these conditions - i.e. is the oil still performing to specification AND is it still clean enough after 6,000 / 10,000 / 18,000 miles? It may be that some of the more expensive oils last a little longer but I suspect your £5.99 Trago Mills oil is still pretty good when you drain it at 5,000 miles. (Particularly if your injectors are in good shape as this is probably the main cause of soot particles in oil.)

The cost of the analysis is potentially more attractive the more costly your oil.

There are other benefits though - the analysis also appears to offer an opportunity to obtain quite a bit of additional information about the state of the engine. Something you don't get even from the better garages these days. I suspect there's a lot more value to be had getting this analysis done - say every 6,000 miles - than having the local Citroen dealer oil door locks (or whatever it is they do at a 6,000 mile service) at £60 an hour.

For those of us doing our own DIY maintenance - and saving a good bit of cash anyway - is this analysis a worthwhile insight into the state of our motors - and at £15.98 every 6,000 miles - does it represent good value. I think it's worth a try personally.

Hi All

Would it be worth regular oil sample analysis for XM auto boxes. Would it help with the sealed for life/regular change debate.
I know from my former work experience that routine nightly oil sample taking from high speed multi cylinder diesel engines can be used to determine future maintenance needs and minimise service failures. They also fitted the engines with data recorders radio linked to ring in with little things like variations in cylinder exhaust temperature, coolant and fuel tank levels.
I understand that many lorries these days have active oil filters and get 100k from the continuously cleaned oil.
For an XM owner to start sampling engine oil on an individual basis would be much less effective than if we pooled our results either through this site or CCC. Would make an interesting addition to the vehicle history when you make the classis sale.


I don't have a diesel XM, but have run diesel pugs in the past. As Roy & Peter have said, on a diesel car the lubricant qualities of the oil long outlast the detergent qualities. This suggests to me that the regular oil changes at 5-6K miles is best -using the most cost-effective oil that meets the grade (Trago Mills, lidl, Netto, etc - all do reasonably cheap, but good, oil).

Yes, modern oils are much improved and long-lasting, but remember manufacturers are now judged on cost-of-ownership and the less servicing they need the better it looks for the company. Doesn't matter to them if the engine only lasts 130K miles - it'll be out of warranty by then and even if it does fail it'll be under 'fair wear & tear' so no comeback.

Petrol cars are a different ball game altogether - using a modern fully synth the oil stays in grade much longer and if the engine is in otherwise good health the intervals can be safely extended by 50%. I've proved this on my mitsubishi (two turbos that cook normal oil very easily!) I had a sample done - Mitsubishi intervals are 6K- oil was Amsoil fully synth - was still in grade after 6K and the lab report said it was good for another 3K miles.

Hi XMexec,

That's really interesting.

For an XM owner to start sampling engine oil on an individual basis would be much less effective than if we pooled our results either through this site or CCC.

Well - I've bought one of the kits now. The guy selling them (Steve) seems very helpful and has offered to do additional interpretation of the test results and store it all on his database. I'm more than happy to pool my results either through him (if that's possible) or by some other means so they can be scrutinised here or on CCC.

If you're going to give it a go - you might want to check this out with him - or let me know if you want my data. Same goes for anyone else.


I understand the analysis also checks the effectiveness of the detergent additives.

Interesting that you've been down this route already.

PeterN's approach makes absolute sense of course - good quality oil at a bargain price - changed at a point where it's still giving great protection.

It's an interesting alternative though. I'm particularly keen on the fact that it could give advance notice of head gasket failure or other problems.

Hi all / mackay 1,

Very interesting, I would give that a try when I get another XM.

When long life servicing became more popular I found it intriguing but having recently seen a very new Saab 3ltr TID diesel and Renualt 2.2 ltr DCI diesel both "grenade" at relatively low miles i'm not so sure. I totally appreciate the huge increases in oil quality but am not convinced about oils changes up to 20k mls.
I have always changed oil and filter on diesel cars at 5k mls with no engine problems.


XM v6 sadist
Hi Mark

I was thinking of buying a Saab 95 with the 3.0l diesel about a year ago but they have a really poor reputation. Apparently quite a few of them have had there blocks go so I didn't buy one.

The other thing to remember with big service intervals is that many company car drivers never check oil levels. Not great with this sort of service intervals.


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