FWIW, my brother is service director at a large Toyota dealer chain, and has had numerous cases of customers returning cars after servicing claiming that the oil had not been changed.
Because the oil had turned black almost straight away.
(Same brother probably won't talk to me this Christmas as I have bought a Citroen XM...)
BTW, any Citroenists out there got any timescales for LHM turning green to brown? Quite quickly, it seems. Any comments welcome.
rg
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The LHM on both the CXs I used to own always stayed green. I don't want to worry you but I thought if it went brown it indicated a problem. Perhaps Mr LHM could enlighten us?
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Rob,
At two/three yearly change intervals our LHM hardly goes badly off colour over its life.
For interest I've just drawn a sample from the Xantia (at 2yrs 4mths - due soon) and it is still green with a hint of yellowing.
MM
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Hm, not convinced about this, although my experience relates to petrol engines. If the oil goes black immediately it's not being changed often enough. Clearly there is crud deposited in the engine which the new oil is (as has been commented) picking up. This is there because the previous oil was left there too long. I've always been of the view that a very quick colour change to black is bad news - there's deposited sludge in the engine.
It should take a thousand or two to get much colour - always does on my petrol engines.
Regards
John S
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Exactly right, John. The synthetic oil, being higher in detergents, will tend to scavenge all the sludge which tends to build up in an engine. Certainly in a petrol engine I would expect it to stay cleaner for longer after a couple of changes, or even straight away if the engine had been looked after. Not so sure in a diesel though as they tend to run much dirtier.
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There is no comparison between the colour of diesel engine oil and petrol engine oil. Run a sound petrol engine for 100 miles after a change and there will be almost no darkening, a diesel is capable of turning the oil quite black in that time.
After a while you become aware of differences in the blackening and it is my view that engines left for 10K+ (rather than 6K) between oil changes will turn the oil black far more quickly.
MM
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Three things ensure golden oil for a good few miles. 1) Make sure engine really warmed after a long run. 2) Tilt car so sludge runs towards drain plug [both as per Vansboy above] and 3] have a cup of tea and read the paper for an hour while it drains - it drips for a surprisingly long time producing a surprisingly large amount.
Garages quite reasonably have no time for this somewhat obsessive approach!
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I agree John F. I have always done my own oil changes on my past cars.B.M.W have serviced this one from new.Last oil change by B.M.W.After reading all oil change interval threads,I decided on intermediate change at 5k Had it changed at Quik Fit so leaving it to drain was not an option I had.
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Think the old diesels (none common rail) turn the oil black almost immediately. That is certainly true of my old BXs where dipping to check oil after running for a few minutes after an oil change reveals black oil - doesn't matter the quality of oil. However, on my wfe's Xantia HDi the oil has remained "clear" for several thousand miles (though I change oil after 5K)
as for LHM it should not be "brown" - it indicates that it needs changing. Maybe your filters in the LHM tank need cleaning as well??
There is a good article on this somewhere on the web - will try to find the link for you
PhilW
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MM, Phil W, et al,
LHM was changed at 36,000 and is next due at 72,000 with filter rinse. Current mileage 65,000, so I suppose that it is permissable for it to be less than pristine green. No serious suspension troubles (this morning, anyway). Thanks be to God.
Do learned members think that the Cit LHM change intervals are a bit too far apart?
And "to flush or not to flush?" Discuss. (20 marks).
Comments from the XM forum suggest that this is only for neglected systems, and should not be used as a precautionary measure. It can find leaks (synth. oil syndrome.)
Conversely,it has been said that it can expose things that were due to go "pop, whoosh"/"ooze, drip" anyway. Better to find them on your own drive than half way down the M3 at 1715 in a rainstorm in December (I live in N. Yorks).
rg
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Rob,
Well I buy the LHM cheaply and it is no trouble to change every 2/3 years.
Personally I never use the flushing fluid and would rather go over the top with the change interval.
MM
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LHM links:-
www.aussiefrogs.com/snippets/lhm_story.htm
www.aussiefrogs.com/snippets/lhm_story2.htm
www.tramontana.co.hu/citroen/suspens/suspens.html
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Wouldn't argue with MM (just been to his web-site to see if I could find words of wisdom re LHM there!). However, postings on BX board seem to suggest that Hydraflush (from Pliades or Andyspares) can work wonders on NEGLECTED systems since it cleans out height correctors etc. Perhaps your LHM is really just due for a change (nearly 30k since last?)despite what Cit say and more frequent changes are the answer as MM says. My BX has had it changed about every 30k and it doesn't become markedly discoloured
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Thanks, Phil,
This is one of the (the many) things that sent me down the Cit route instead of Omega; So much knowledge out there, outside the realm of the dreaded main dealers. Plenty of good Cit workshops, proprietors with dirty fingernails who actually drive and cherish Cits.
(Or maybe I am still in honeymoon mode?)
David, have you got your own LHM plant out on Tick Fen, or can you name your LHM source? (Does it bubble to the surface through the peat?)
Does degradation of the LHM cause premature rack wear, amongst other horrors?
FWIW it's a kind of greeny-brown. I may get the Cit man to change it at the 66K service ISO 72K at this rate.
Thanks chaps.
MM - Prompt responses to mails this morning. Are you, like me, putting off outdoor work?!!
rg
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Rob,
The honeymoon (and expense) is never over with a LHM suspended Citroen!
They can get you everything else at Tick Fen but no LHM plant yet.
Isn't it only about £3.50/lit retail at Andyspares/GSF (I get trade and like the Bendix stuff they do in tins).
At the PC too much this morning because I'm waiting on a new cylinder of propane for the workshop heater so I'm doing final customer Xmas cards at the PC...and in the warm.
MM
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Changed the oil in the Rover the night before last.
Checked it this morning [1],27 miles later it's black enough that I can't see through it...
[1] Long drive home tonight for Xmas.
--
These are my own opinions, and not necessarily those of all Toads.
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Left in far too long last time I would say then...if it was a £3K plus car I'd change it again soon.
On a sub £500 machine.....well at least you changed it once!
MM
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My dad's Micra's oil was dark, but still see through after 9,000 miles. My Fiesta's is no longer very see through and has gone very dark, and it's only done 6,000 miles. But then, these were almost all city miles, whilst the first 5,000 miles on the Micra were mainly motorway...
Blue
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Yeah! I was tempted to flush it few times but won't be spending 10 per cent of the vehicles value on cleaning the inside of the engine!
I will change it again in the spring (maybe 4 months?) then go to my 6 month change regeme regardless of mileage.
The previous owner claimed to change oil every 6 months (but never the water which is cloudy) Interestingly the filter was finger tight and the sump plug came of easily which supports his change. The old oil was *very* black though.
--
These are my own opinions, and not necessarily those of all Toads.
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To summarise -
Diesel engines dirty the oil much sooner than petrols.
Semi- or full-synthetic oil loosens any sticky crud when used for the first time.
If you don't drain the sump fully, the oil can still look black a few miles later. So always drain after a run of at least ?8 miles, with the car at an angle where the drain is at the lowest point, and allow at least 10-15 minutes (if you have time to spare - drain before lunch and refill afterwards!).
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I'm a bit late coming in on this one but it is a fact that diesels blacken the oil within a very few miles, much faster than petrol engines. The reason is that when diesel fuel is combusted it produces carbon, some of which is deposited on the cylinder wall and finds its way into the oil.
Diesel oil blackening took a turn for the worse a few years ago because fuel injection timing needed to be retarded to help reduce emissions, typically being moved from BTDC* to ATDC*. This means that the piston is already be on the way down when the bulk of the fuel is injected and so a greater length of the cylinder wall is exposed to the combustion event. The situation may have improved recently because modern very high injection pressures should be producing cleaner burns.
I don't think the colour of the oil can be relied upon to indicate its condition. What is often overlooked is that oil-change intervals depend largely on the oil capacity of the engine; i.e. the more oil there is, the more dilute the contamination. Carbon is probably the most damaging contaminant of diesel oil and should be kept below 2% by volume, though this is almost impossible to measure outside of a laboratory of course.
(* BTDC = Before Top Dead Centre and ATDC = After ....)
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Dizzy
I'm a bit confused about this 2% carbon. Diesel, as a hydrocarbon fuel, is about 85% carbon. Did you mean ash?
Regards
John S
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John,
I believe that our human bodies are also comprised mainly of carbon but we couldn't exist on a diet of it (although I do like my toast well browned!).
The carbon I was referring to is fuel that is incompletely combusted so 'ash' is probably a fair description. I'm not a chemist but the term 'free carbon' might also be somewhere near correct.
To expand on my original posting, the larger the fuel droplet size and the more 'dead spaces' in the combustion chamber, the higher the propensity for incomplete combustion. Very high injection pressures help atomise the fuel into an extremely fine spray which will burn through more thoroughly and so leave less residue to contaminate the oil and the environment.
Pilot injection also helps because it 'lights the fire' before the bulk of the fuel is injected, thus aiding complete combustion. Pilot injection also reduces the speed of pressure and temperature rises within the cylinder to reduce noise and NOx emissions respectively.
These advances mean that we are getting forever closer to diesel engines that will produce ultra-clean exhausts without the need for after-treatment devices like particulate traps. The problem in the past was that improvements in particulate and nitrous oxide emissions, and specific fuel consumption, were always a trade-off one against the other, i.e. an improvement in any one of these three areas would lead to a deterioration in one or both of the others. Thankfully that 'trade-off' barrier has been broken and that is why we are now seeing relatively quiet, powerful and clean diesel engines.
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My last line should have read " ...quiet, *economical* and clean ..."
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Dizzy, John S - the term you are looking for is SOOT (speaking as an ex-chemist).
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Andrew
In the power industry we call it 'carbon in ash' - a measure of combustion efficiency.
Regards
John S
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Yes, John - and in the rubber (tyre) industry it is called carbon black.
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"Pilot injection also helps because it 'lights the fire' before the bulk of the fuel is injected, thus aiding complete combustion. Pilot injection also reduces the speed of pressure and temperature rises within the cylinder to reduce noise and NOx emissions respectively".
Dizzy,
Volvo have implemented pilot ignition on the new D5 engine so I suppose that is why the engine is relatively quiet for a diesel and why the oil stays relatively clean between changes. There is also no particulate trap so I imagine Volvo see no need for one as the exhaust emissions must be reasonably clean.
VD5D.
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You're probably right, VD5D.
It's only the very advanced injection systems that can do pilot injection. It can't be done with the old pump-line-nozzle system or even with some of the unit injector systems. As you can imagine, metering a precise charge of fuel is going to be much more difficult if it's being injected in two lots as there will be twice as much room for error.
Andrew -- yes, 'soot' is indeed the word. Thanks for jogging my senile brain.
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