High-Mileage V8 Diesel - 5W30 or 5W40?

[E55BOF]

My ML420 diesel has done 980 miles since it's last service six weeks ago, and it says it wants a litre of engine oil. It has now covered 156K miles. At that mileage I'm minded to use 5W40 rather than 5W30 (Mercedes-approved 229.51 SPAsh oil, naturally; there are plenty of suppliers of 5W40 on the list) to see if I can curb this thirst a little. Does anybody think that would be a bad idea?

 

[bob6600]

I don't see why not, a litre after 980 miles is some thirst! I would try the 5w40

 

[350cls]

I would stick with the 5W30 monitor it, see if it asked for another litre a1000 miles down the line. Then it will give you an idea what consumption it's drinking with that grade. Then do a swap to the 5w40. And see if your consumption drops. It is a big old firstly V8 diesel at the end of the day.

 

[350cls]

Sorry to drop the old in there lol

 

[Bellow]

I'd try 10W30 first as I don't like the two numbers being too far apart. And if that doesn't do the trick, 10W40. Just take a bit more care during warm up if a higher W number oil is used.
The W part is the oil. The second number is viscosity improvers which break down under shear conditions.

 

[SW18]

A consumption of 1 litre per 1000 miles is still within manufacturer tolerance, isn’t it? I used to have a BMW that got through a similar amount - I started to wonder why bother doing annual oil changes since the oil was getting fully replaced in the meantime anyway!

 

[Teego]

A consumption of 1 litre per 1000 miles is still within manufacturer tolerance, isn’t it? I used to have a BMW that got through a similar amount - I started to wonder why bother doing annual oil changes since the oil was getting fully replaced in the meantime anyway!

Me too, but you don't get rid of the crap in the system.

 

[E55BOF]

I would stick with the 5W30 monitor it, see if it asked for another litre a1000 miles down the line. Then it will give you an idea what consumption it's drinking with that grade. Then do a swap to the 5w40. And see if your consumption drops. It is a big old firstly V8 diesel at the end of the day.

The first fill was done by Terry Gates, using MB's own 5W30. The car said the oil level was OK. It's asking for a litre now, so I know the consumption with the 5W30.

It is an old engine, so no offence taken.

I'd try 10W30 first as I don't like the two numbers being too far apart. And if that doesn't do the trick, 10W40. Just take a bit more care during warm up if a higher W number oil is used. The W part is the oil. The second number is viscosity improvers which break down under shear conditions.

MB do not approve any 10W for the 229.51 SPAsh specification; they're all 0W or 5W.

I'm going to put this in:

https://www.ebay.co.uk/itm/MANNOL-FORMULA-PD-5W40-DIESEL-ENGINE-OIL-5-Litre-5-40-AUDI-VW-1-9TDi-dexos-2-C3/322300553948?ssPageName=STRK:MEBIDX:IT&_trksid=p2060353.m1438.l2649

It's very cheap, but it's in MB's 2019 approved list; that's good enough for me.

 

[MercedesDriver]

The first fill was done by Terry Gates, using MB's own 5W30. The car said the oil level was OK. It's asking for a litre now, so I know the consumption with the 5W30.

It is an old engine, so no offence taken.



MB do not approve any 10W for the 229.51 SPAsh specification; they're all 0W or 5W.

I'm going to put this in:

https://www.ebay.co.uk/itm/MANNOL-FORMULA-PD-5W40-DIESEL-ENGINE-OIL-5-Litre-5-40-AUDI-VW-1-9TDi-dexos-2-C3/322300553948?ssPageName=STRK:MEBIDX:IT&_trksid=p2060353.m1438.l2649

It's very cheap, but it's in MB's 2019 approved list; that's good enough for me.

Or even better this:
Shell Helix HX8 ECT 5W-40 - 5Ltr | Euro Car Parts
And with mid60 code it comes to £18.

 

[clk320x]

What sort of journeys are you doing? Are you driving the car hard?

 

[Gazwould]

Oil is an easily confused and forum member misleading subject .

We've already had the recommendation semi synthetics and a incorrect grade description !

Has the ML a dpf thus requiring low saps ?

1L isn't horrendous as the engine will have an 11+L oil capacity , and if going to 40 grade some are thicker than others as in any oil grade .

 

[T5R+]

OP/Anyone - this is a little off topic ........do you have a manual dipstick? if so, where is it please?

 

[E55BOF]

Has the ML a dpf thus requiring low saps ?

It's a twin turbo engine, and has two DPFs.

What sort of journeys are you doing? Are you driving the car hard?

Not exactly hard, I'd have said, but I'm aware of the engine's potential for sludging up the inlets, and tend to take the long way round, with a quick squirt up the motorway and back too, most times I use it. When I bought it I checked the DPF ash contents, and both were pretty low - single figure percentages, ISTR - so it's had some work there recently, and it's reasonable to suppose that if the then owner spent an armannaleg getting the dismantling done for that, the inlet side would have been sorted if necessary as well. It does at least one, and more usually two or three, forty-mile, mostly motorway, round trips commuting to Heathrow, not in the rush hours, at 80mph/2200 rpm (or more, but I'm not admitting to anything...) per week, and some longer trips as well, and I bite the bullet and Shell out (see what I did there? Oh, all right, please yourselves...) for V-Power diesel too. I reckon all that has a good chance of keeping it clean.

 

[E55BOF]

OP/Anyone - this is a little off topic ........do you have a manual dipstick? if so, where is it please?

Yes, on my 2007 ML420 it's front left (as you look at it) of the engine. The knob on the end is black.

 

[T5R+]

Yes, on my 2007 ML420 it's front left (as you look at it) of the engine. The knob on the end is black.

Thank You. Partly asked as my electronic/dashboard and manual dipsticks are not consistent. Assume that you have checked both.

 

[st13phil]

I suppose the real question is “where is the oil getting to the combustion chamber from?”

Logically it’s either past the rings, past the valve guide seals or through the turbo seals. Oil grade might make a (minor) difference to one of those, but is unlikely to have any effect on the other two.

 

[grober]

If your car is running the OM629 it will have Garrett GTB1752 VK [ electronic actuation] turbos. Your excessive oil consumption might be down a problem with one or both of those?
Mercedes-Benz OM628 and OM629 engines
https://www.melett.com/wp-content/uploads/2016/12/TurboFailureMatrix.pdf

ps replacement cartridges are available?
Garrett GTB1752VK Turbocharger CHRA Cartridge Turbo Core 787630-0001

 

[190]

5W40 will do no harm at all.

When choosing a brand of oil to the correct MB spec if you can access oil data sheets then look for the lowest NOACK number which is a test for evaporation losses. MB spec oil has a good NOACK number anyway of 10% but lower is better still. Evaporation is of course only one reason and probably a minor reason for oil usage but together with the higher viscosity it may help.

 

[E55BOF]

Thank You. Partly asked as my electronic/dashboard and manual dipsticks are not consistent. Assume that you have checked both.

I haven't bothered checking the actual quantity of oil in the sump using the electronic system. After the service, the dipstick showed about two-thirds full, and the electronic check said 'Level OK'. On a petrol car I normally top it up to the full mark on the dipstick, but I'm mindful of the possibility, however remote, of an overfilled diesel engine runaway, where it runs on its own oil until it self-destructs, so I'm content with two-thirds full as a starting position.

It's not using a worrying amount of oil, and there's no smoke from the exhaust at any time, so I'm not greatly concerned about it; indeed, I wouldn't even describe it as excessive, but I'd rather it used a little less.

 

[DSM10000]

Is the level sensor working correctly?