Thread: Front and rear diffs - oil full of metal flake

I'm another that considers oil as cheap insurance. In fact I could probably be classed as an oil fanatic.....it started many moons ago when I was maintenance fitter in a place in the UK and the boss employed a bloke whose job was solely to service his car, his wife's car and racing car.
He reckoned the best thing was regular oil changes to ensure longevity of all components and we had plenty of oil. So every 2 weeks when I was on late shift my oils got changed.
Now I'm not quite as bad as I have to pay for the stuff but the D4s engine gets changed every 10k plus filter of course and the Defender I just sold had the same plus diffs and boxes every 40 kay.
When under warranty I get the stealer or indie to do the changes.
I like it that way and ain't gonna change now.
AlanH.

PS. The company I worked for which made me like this used asbestos in many of their products so maybe I can blame that for my actions.......

D3 & D4 are starting to get a few runs on the board but it's obvious we are still on a bit of a road of discovery (pun fully intended :-)). Usage, servicing, manufacturing flaws and errors will all play their part on how these cars age.

All things being equal, regular lube changes with the correct product should be a good insurance policy..... but...

As has been inferred here, missed by others, very regular oil changes can actually mask a component under stress. That can mean the difference between a mechanical operation (repair) and a complete heart attack (snapped crank, blown diff, etc). Changing the lube will not prevent some of these things occurring. However, early detection can mean the difference of a few $, few hundred $ or several thousand $.

Aviation lives and breathes health analysis …. oil tests can tell you exactly which parts are wearing due to the particles in the oil. On going analysis can tell you which parts are wearing too fast … either by the quantity or the frequency (data over time) that the material is being detected. Foreign contaminants also get flagged. This methodology has moved into heavy industry. It's too expensive to let a big mining truck fail … and then fix. Predictive, preventative maintenance is the way to largely avoid these issues. Oil sampling is one of the many inputs and factors considered.

So back to Discos …. an owner can theoretically avoid a massive, expensive failure by letting the car produce some markers in the lude and getting it tested. I guess if you turn over cars often, it probably doesn't matter to YOU. But if you want to keep the car for years, it maybe will. These cars are not old school …. they are both electronically and mechanically complex …. and they are not cheap to repair.

I think that is the point of Tombie and ConMon's input.

Originally Posted by Celtoid

D3 & D4 are starting to get a few runs on the board but it's obvious we are still on a bit of a road of discovery (pun fully intended :-)). Usage, servicing, manufacturing flaws and errors will all play their part on how these cars age.

All things being equal, regular lube changes with the correct product should be a good insurance policy..... but...

As has been inferred here, missed by others, very regular oil changes can actually mask a component under stress. That can mean the difference between a mechanical operation (repair) and a complete heart attack (snapped crank, blown diff, etc). Changing the lube will not prevent some of these things occurring. However, early detection can mean the difference of a few $, few hundred $ or several thousand $.

Aviation lives and breathes health analysis …. oil tests can tell you exactly which parts are wearing due to the particles in the oil. On going analysis can tell you which parts are wearing too fast … either by the quantity or the frequency (data over time) that the material is being detected. Foreign contaminants also get flagged. This methodology has moved into heavy industry. It's too expensive to let a big mining truck fail … and then fix. Predictive, preventative maintenance is the way to largely avoid these issues. Oil sampling is one of the many inputs and factors considered.

So back to Discos …. an owner can theoretically avoid a massive, expensive failure by letting the car produce some markers in the lude and getting it tested. I guess if you turn over cars often, it probably doesn't matter to YOU. But if you want to keep the car for years, it maybe will. These cars are not old school …. they are both electronically and mechanically complex …. and they are not cheap to repair.

I think that is the point of Tombie and ConMon's input.

I see the logic in what you say and it does make sense. So, how long do you need to leave the oil before the indicators you speak of are apparent? In my case for example, I follow a time schedule as I don't do enough Kms to work on mileage.

Martin

Originally Posted by trout1105

Isn't it better to have 0 parts per million by changing the oil??

Of course - but in reality that will never happen. There will always be trace particles left after an oil change and though usage you are creating more wear particles all the time.

Originally Posted by DiscoClax

Shane, interesting numbers. I'll put my ignorance out here for all to see, but I thought that those sorts of iron concentrations were a bit on the high side? Wouldn't something closer to 100ppm (or at least <200ppm) be a better place to operate? Not my area of detailed knowledge so looking to learn something.

I'd hate to know what mine was. It'll likely be >1000ppm still after the oil change given the metal paste settled in the bottom... Front was a visibly a bit cloudy too, which means the moisture content was way above safe levels.

the numbers look high, and IMHO they are for me the changeout limit for this application - the 1000ppm limits mentioned would most likely be applying to truck differential - stuff with bigger clearances and bigger capacities. Also worth noting that those figures are derived from particles less than 10 microns in size

Originally Posted by trout1105

I do understand what ConMon is saying But I would much prefer to change the oils in engine, transmission and diffs frequently as a preventative maintenance program, Getting the oil analysed and only changing it when it is on its last legs is unacceptable for me personally.
I am of the belief that changing out the oil BEFORE it starts to degrade or gets contaminated is a much better maintenance regime that waiting until the oil is practically useless and only changing it at that time.
Components running in nice clean oil will always outlive components that have been left to run in substandard oil.

Theres more to looking at samples than simply waiting for the oil to be degraded before a changeout - In fact I'd say I've rarely changed oil due to the oil purely degrading from normal use. 99% of the time (this includes at work as its just one part of my job) I'll have oils changed due to contamination levels. Sometimes the contamination is from an external source (dirt, grease, fuel etc) and in some cases its from wear. I'll always change the oil before its completely shagged as I will always allow a buffer to be on the safe side.

And Tombie made a good point about getting new oils tested - I can be amazing how dirty some of it is, we have gearboxes at work (iron ore mine) that have cleaner oil thats not been changed for over 5 years

Originally Posted by letherm

I see the logic in what you say and it does make sense. So, how long do you need to leave the oil before the indicators you speak of are apparent? In my case for example, I follow a time schedule as I don't do enough Kms to work on mileage.

Martin

It's a really good question Martin and the answer is a bit convoluted.

For the record, I wouldn't even know where to take auto oil for testing as my experience is based on my aviation industry past. I'm also not sure if auto oil testing is as comprehensive as aviation testing, but for the sake of the conversation, let's say it is. Which means checking the oil/lude's general health and contaminant level (metals and others things floating around).

For ease, when I say 'good oil' I mean correct spec, correct additives and in good health. When I say 'bad oil' I mean wrong spec or additives or in poor health …. or all of those.

The relationship of oil condition and component health isn't directly proportional either. You can have components in stress that all the good oil in the world won't help. The good oil may prolong the life but the component could still fail while bathing in that oil. Conversely, if you are running bad oil, your components will most certainly fail at some point.

Components will break down/wear over time … that's normal and that's expected. Testing is to find when the 'normal' parameters get exceeded. Many aircraft have magnetic plugs in their engines and drive train components to collect the normal amount of waste. Some have a thing called Fuzz-Burn, that electrically burns off waste of insignificant size, on the magnetic plug. These plugs are cleaned and the oil sent for testing during the aircraft's routine service schedule.

However, in case things are not normal, many aircraft have Chip-Detectors which give the pilot an indication in the cockpit. This usually means that something of significant size has come to rest on the plug and isn't getting burned off. This usually constitutes adverse condition procedures initiated by the pilot e.g. Engine shut down or retardation and often an emergency landing (where possible).

Back to your question …

In theory if you were regularly testing your oil for contaminants you wouldn't need to set a timeframe for an oil/lude change, as you would get close to real time health monitoring. Healthy oils and components will wear/breakdown at varying rates due to the type of usage they are subjected to. However, this isn't practicable for most people to keep sending their oil off for testing. One would assume that manufacturers conduct testing and the set intervals are based on an average point where some folks will be dumping oil that is still in very good nick and others will be dumping theirs close the end of the oil's useful life. However, the extended service regimes of modern cars may indicate that this is no longer the case.

Not clocking up enough Ks in a 12 month period, as is the case for you, could be considered arduous driving, as the oil gets broken down due to the fact that induced contaminants like fuel vapour and water don't get boiled off in the short driving timeframe. Maybe if you are doing decent drives of 30+ minutes but just not driving the car very often, you'd be OK. I know guys with 'their special cars' … Porsches and the like, that only drive them once a month or something. But that drive is all day long so the lubes are well and truly heated up and circulated. They service based on date, not Ks. I volunteer to drive their cars more often …. stone-wall!

As stated by others, the component will never be truly clean, so oil contamination will occur almost immediately so it's a matter of how long it takes to get to a point where the oil is not performing as it should. That should be well outside the promulgated service schedule. So a useful testing point would be at the point of service. If you wanted to be really scientific you'd do what the car manufacturers should be doing and test the oil at regular intervals to see where the breakdown point occurs. You'd then pick a time before that to carry out ongoing servicing's. Of course your driving conditions would have to remain pretty consistent for that period. The benefit of this 'baseline' though, is the fact that you can adjust your servicing schedule accurately to suit the driving conditions. If you do a lot of unusual arduous driving, you service earlier. That sounds eerily familiar ….. it sounds like a service schedule that should be in the OEM manual … LOL!!!

I guess the point of this whole topic is the lack of trust in the OEM and owners attempt to find out what is right for their car and usage.

Me, I just change the oil every 10 thousand Ks or there about. I usually get two servicing in a year. I do a mix of short hops but regularly do 1 hr plus drives, so I'm not overly concerned. Now that my car is hitting 70 thousand, I'll probably talk to an indie about getting the drivetrain looked at soon.

I know my ramble probably didn't help you Martin …. but you did ask … LOL!!!

Originally Posted by Celtoid

I know my ramble probably didn't help you Martin …. but you did ask … LOL!!!

Thanks Celtoid. Appreciate the time spent typing it. You're right in assuming my driving would be arduous. Lots of 5 to 10 kilometre trips with a few 80 kilometre runs down to Wollongong where my sister lives and the odd 30 minute drive. At the moment I have a mini service at 6 months to help and have the oil and filters changed then too. Given my driving regimen I feel happier doing that. No real science behind it for me, just seems to be a good preventative maintenance thing given the driving I do.

Martin

I have no doubt that regular oil testing in aircraft engines is a critical safety issue and also a financial issue as well But I do find it hard to justify the time and expense to get these test done on a run of the mill car/4WD.
What the real issue here is the extended mileage/time between services on the newer vehicles AND the "Quality" of that dealer services.
Even if the oils are not to be changed at a particular service a "Competent" dealership would at least check the fluid/oil levels and physically check the condition of those fluids/oils.
As in the OP's case this was obviously not done or even worse the condition of the oil in his diffs was simply ignored on prior services.

For what it's worth I don't think that you can check the oil level on the the D4 diffs, you can only drain and refill with the correct amount of oil. That is how it reads in the manual anyways, I have not changed my own diff oil yet.