Changing oil in Diesel CDI - Frequency

[hampshire]

I'm getting conflicting information about the frequency of changing the oil / filters in my Smart CDI Diesel engine 2012 model.

I bought the car from Mercedes of Poole and it had 3500 on the clock. They did a 'general' service including changing the oil.

6 Months later, Im up to 6500, so i have clocked up just 3000 miles in that period. The oil looks black. Some reports suggest getting the oil analyised. Some say the oil should be changed after 3000 miles, but the Merc Dealer are saying, once a Year is good.

My smart does mainly town driving with the occasional longer trip.

Any suggestions or pointers are appreciated

Thanks, Tony

[Evilution]

Re: Changing oil in Diesel CDI - Frequency

1 year or 12,000 miles. Ignore the 3000 mile nonsense, that is a myth from America.

Of course the oil is black, diesels are dirty.

[Thrumbleux]

Re: Changing oil in Diesel CDI - Frequency

Beg to differ Evil - it's a homegrown nonsense not an American one! America is all about extending servicing intervals as far out as possible (that's why they invented hydraulic tappets - as they found on their lazy V8s that rocker tip wear was driving the servicing schedule needing manual adjustment as they did) hence they champion long drain oils.
The UK obsession with changing oil every ten minutes is borderline fetishistic and if honestly required points to the oil used being sh!te. Just because a race car has its oil changed after every race doesn't mean a road car needs the same mollycoddling.

[Evilution]

Re: Changing oil in Diesel CDI - Frequency

From the research I did for this page, I disagree.
http://www.evilution.co.uk/911

It may be prevalent over here but it started over there and is still widespread. Even servicing companies like Jiffylube recommend a 3000 mile service on every car (to boost profits by scaremongering). Over here, garages don't do that, only clueless owners.

[Thrumbleux]

Re: Changing oil in Diesel CDI - Frequency

From the research I did for this page, I disagree.
http://www.evilution.co.uk/911

It may be prevalent over here but it started over there and is still widespread. Even servicing companies like Jiffylube recommend a 3000 mile service on every car (to boost profits by scaremongering). Over here, garages don't do that, only clueless owners.

It's the context here in which we're at odds. Yes I concede that Americans got used to short drain intervals and the way their engines were set up to some degree demanded them. But, it was also American companies (one in particular) that pioneered long drain oils (primarily for industrial - road haulage, off-road excavation, rail-road, elec generation, etc) in conjunction with oil analysis to determine the new, safe, drain interval. This aspect is one that Europe has never truly cottoned on to - the possibility of extending drain intervals over the OEM's by whole number factors.

''Using 0W in a smart engine in anything but a cold climate will cause faster engine wear
on cold starts and won't properly lubricate until it reaches full operational temperature.''

Re the above, not so.
The problem with cold start is always about getting cold thick oil to flow quickly enough to the bearings. The thinner the better. The problem then lies at the other end of the temp scale as at low temps the base oil is doing the work. But as temperature increases the viscosity of that oil is too low and will shear, ie, insufficient film strength will lead to rupturing of the oil film. To deal with that the thin oil is fortified with viscosity improvers (VIs) which are long chain polymer molecules which close when cold (like a clenched fist) and open when heated (open hand, spread fingers). Thus being more expanded and bulkier they increase the viscosity hence the higher (eg, 30, 40, upper temp number).
However, they are vulnerable to being 'chopped up' (chains, gear trains give them a hard time) and when they do the oil goes 'out of grade' at higher temps - leaving only the thin (0W) oil to protect and it isn't up to the task.
That's why I advise against oils with low W numbers and high upper numbers. The difference is bridged by VIs - and they are vulnerable.

[tolsen]

Re: Changing oil in Diesel CDI - Frequency

That pioneering company is Caterpillar and I worked in one of their oil labs during the seventies, more than forty years ago.

I agree 0W grades are not required in the UK but strongly doubt they are harmful as suggested by some.

[Cie]

Re: Changing oil in Diesel CDI - Frequency

This is a great thread.

Interestingly the manual in my new (to me) '10 451 CDi doesn't really recommend an oil which I wasn't expecting. The chart in there shows that you can use all sorts of grades.

[Thrumbleux]

Re: Changing oil in Diesel CDI - Frequency

That pioneering company is Caterpillar and I worked in one of their oil labs during the seventies, more than forty years ago.

And which company did Caterpillar turn to for long drain oils? The one established in the 1950s?

[Evilution]

Re: Changing oil in Diesel CDI - Frequency

The chart in there shows that you can use all sorts of grades.

Grades depending on your expected climate temperatures.

[tolsen]

Re: Changing oil in Diesel CDI - Frequency

Even UK's coldest place, Braemar, does not enjoy average outside air temperatures below zero degrees C. Based on that and the table in our handbooks, we could all run on 20W-50 grade engine oil!

[Evilution]

Re: Changing oil in Diesel CDI - Frequency

It was -5 near London a few days ago.
Average climate temperature is no good, expected range is what you need.

[Cie]

Re: Changing oil in Diesel CDI - Frequency

So that'll be -10C to +30C typically, certainly in the south, which equates to SAE 15W30...?

[tolsen]

Re: Changing oil in Diesel CDI - Frequency

Lowest average temperature is not particularly low anywhere in Britain where Smarts can go. Example:

London:



Braemar:



Surprisingly, the difference in lowest average temperature is no more than three degrees C.

According the official Smart recommendation in our handbooks we can safely use 20W-50 engine oil but those running diesel Smarts may have trouble starting certain mornings. Wonder what grade the Braemar Smart Centre would recommend.

[Evilution]

Re: Changing oil in Diesel CDI - Frequency

That's like telling a 100 year old person that his average age is 50 and he should walk to the shops.

[tolsen]

Re: Changing oil in Diesel CDI - Frequency

Copied from the Smart handbook:

Engine oil viscosity
The SAE class (viscosity) has to be chosen in accordance with the average outside air temperature for each current season.

Lowest average outside air temperature for London and Braemar are +3 and -2 degrees C respectively.

Then by consulting the viscosity table in our handbooks one can confirm that 20W-50 is adequate since this grade is good for lowest average temperature of -5 degrees C.