Time based servicing is "generally" a means to part you and your money, however engine oil does need to be changed due to contaminants from the combustion process.

I've run fleets using both time and miles and very often time is a waste of money BUT can lead to under servicing (for high mileage vehicles obviously).

Serious organisations determine their servicing requirements based on Spectrometric Oil Analysis Program (SOAP) testing (including for engine/gearbox and diff oils) and this can vary considerably for many reasons including different drivers, how they drive and whether long or short trips. Even in fleets one identical vehicle can differ from others, hence the companies work out a "Mean Time Between Failure" and service schedules are determined accordingly, to take action before a component/part fails. The aircraft industry also follow this practice.

So presumably if Mazda are not just grabbing your cash, they have based their servicing on research.

Gday...

On the other hand ... generally speaking -

• an engine that does short, infrequent trips needs to have the oil changed on a "time" basis more critically.
• A motor that travels longer distances of longer duration needs to be changed by distance travelled.

e.g. -  A vehicle with service intervals set by manufacturer at 15,000km or 12 months;

• 5,000km over twelve months of short duration, city driving should have oil changed at end of that twelve months. (Although, the service book may consider that usage as 'adverse' conditions (like towing) and should be changed at six months. I know I would be changing the oil at six months rather than waiting until twelve months).
• 15,000km over six months of longer duration trips, highway driving would need to be changed at the 15,000km even though it was only six months.

There is no hard and fast "rule" for oil change/oil filter change for engine longevity. However, for the duration of the warranty period of the vehicle it is prudent to at least adhere to the manufacturer's recommended service intervals.

Cheers - John

DeBe wrote:

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You could save a lot of money by changing just the oil & filter yourself, if out of warranty. Bearing in mind if its the 5cyl diesel don't take too long to do the filter & oil change. As it wont pick the oil up on starting. The cure for that is remove the oil pressure switch & pressure feed oil in to the oil gallery.

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 Could you "please explain" If I take half hour to pour new oil in the engine won't pick it up ? Is that what your saying?

Ok I just couldn't believe it

what about only changing the filter every 5000,would that keep the oil cleaner ... Peter

Hi Sti,

Yes oil contamination does occorr regardless of how many k's you log up.The oil is the life blood of your motor .(Just Remember That)  to lubricate the internal moving parts of your engine. Cylinder lineings valves ,bearings ect.When combustion occorrs very very small amounts of fue l/ carbon gets removed into the crankcase which starts to break down the oils original qualities. The carbon will thicken the contaminated sump oil that is moved around the motor by the oil pump running off the crankcase on a worm drive.The faster the motor rev's / spins the faster the pump moves the oil around the motor.

The longer the oil remains in the motor, the carbon is allways accumulating over time. the carbon is what causers premeture engine ware. Does this make sence to you.

I am a beilever in changing both the oil and oil filter every 5000km on time, especially when toeing the van / boat. Oil and filters are cheap compaired to a total motor rebuild or replacement tug.

My last car a Toyota prado V6 petrol was fifteen years old.I clocked up 455,000 km on it with over half while towing.I had changed the oil /filter every 5000km transmission every 20,000km with receipts for the materials brought.It took five minutes to sell it and I do the same with this one.

Regards Hey Jim

Pollution, carbon deposits, acid deposits etc are caused by driving the car. If the car is only driven for 1000km a year then it will only pollute/carbonup/acid etc the oil to the tune of 1000KM......drive the car 5000km and multiply the pollute/carbon/acid etc by 5X. Oil sitting in a sump cannot be contaminated - the engine must operate for contamination to occur. Think about it.
I've seen cars that never have their oil changed, however this is only on older cars that are well out of warranty. Of all the engine failures I've been privy to most have failed by overheating, timing belt failure or pushing the car beyond normal limits e.g. a red P plater.
My opinions only!

hako wrote:

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Pollution, carbon deposits, acid deposits etc are caused by driving the car. If the car is only driven for 1000km a year then it will only pollute/carbonup/acid etc the oil to the tune of 1000KM......drive the car 5000km and multiply the pollute/carbon/acid etc by 5X. Oil sitting in a sump cannot be contaminated - the engine must operate for contamination to occur. Think about it.
I've seen cars that never have their oil changed, however this is only on older cars that are well out of warranty. Of all the engine failures I've been privy to most have failed by overheating, timing belt failure or pushing the car beyond normal limits e.g. a red P plater.
My opinions only!

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Gday...

I understand your logic and in some ways it is valid. "...Oil sitting in a sump cannot be contaminated - the engine must operate for contamination to occur."

However, if the engine is only started irregularly and driven for short distances (eg - little old lady who only drove it to church on Sundays) the engine oil will be getting a gutful of "contaminants" because the motor and oil are not getting to a proper operating temperature to "burn off" those contaminants.

Apart from the number of Km travelled in whatever time - it is the usage that is quite critical to engine longevity.

Cheers - John

hako wrote:

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Pollution, carbon deposits, acid deposits etc are caused by driving the car. If the car is only driven for 1000km a year then it will only pollute/carbonup/acid etc the oil to the tune of 1000KM......drive the car 5000km and multiply the pollute/carbon/acid etc by 5X. Oil sitting in a sump cannot be contaminated - the engine must operate for contamination to occur. Think about it.
I've seen cars that never have their oil changed, however this is only on older cars that are well out of warranty. Of all the engine failures I've been privy to most have failed by overheating, timing belt failure or pushing the car beyond normal limits e.g. a red P plater.
My opinions only!

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 If that 1000km was done in one hit your argument would be valid. If that 1000km was done in 10 or 20 hits the engine would not be getting hot enough to burn of the pollutants. Water, sulphur & others. Water & sulphur are the bad ones.

Years ago we thought it was good to run engines as cool as possible. Now they run minimum 82 degrees Celsius, to burn of pollutants. If they don't run at that temp for a reasonable period of time these pollutants don't get burnt off.

Basically don't buy a diesel that's only been driven to church on Sundays by a little old lady.

Cheers Pete

I've still got a Frantz filter which uses a toilet paper roll as a filter medium - had it on my old Jag XJ6 and the oil would be almost clean as new when drained every 12 months BUT it could not remove acids, oil dilution or any of the contaminents that are invisible. Haven't been game enough to put it on the Territory. You can still buy them and some are designed for trucks take 3 toilet rolls.
Regards

The dirtier your oil the better it's working at keeping your engine clean..
They have additives in them to combat carbon build up etc..
10,000 klmrs is not a lot of klmrs ..
Given the size of sumps etc these days..
Old v8's run 4 litres ..modern diesels run way more...

Dodge wrote:

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If you have a modern diesel most manufactures recommend 10,000 k oil change? however I do mine ever 5000 k's this is mainly due to the fact my Dodge (and most new diesels) has a DPF (Diesel particulate filter) this filter catches all the carbon (soot) and when the filter is full goes thru a very hot burn process to clean it out again, the bad news is that all the crap then goes into your oil so that it does not go out the end of your exhaust, extra wear on your engine is the result. So changing the oil more often will help reduce the engine wear.
Regards

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 Hi Dodge,

I believe you have misinterperated something here. When the engine does a regeneration on the DPF by burning it out, the stuff goes out the exhaust pipe with the exhaust gasses, there is no where else to go. The DPF is along the exhaust system a bit, it does not have any connections to put the crap into the oil. That would be very strange to do, particularly with a diesel. 

What is important with a DPF is that you use a low ash oil so that the deposits of the ash from the oil that is burnt off are minimised and do not clog the DPF prematurely.

Jaahn

some reading; http://en.wikipedia.org/wiki/Diesel_particulate_filter

-- Edited by Jaahn on Wednesday 29th of April 2015 02:11:34 PM

-- Edited by Jaahn on Wednesday 29th of April 2015 05:28:13 PM

Dodge wrote:

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Hi Jaahn,
The info I gave is what is in my service manual, for my Dodge Ram - Californian (USA) law requires nil to no carbons etc to be let out of the exhaust, hence the two pipes on the DPF filter one leads back directly into the upper part of the sump with an electronically activate one way valve on?????My mechanic of 15 years also informed me the same thing as the service manual, as I was worried as how quickly the oil was turning black, he also stated that is why there is a high maintenance/engine rebuild in the USA with vehicles having a DPF filter on?
Regards,
Wayne

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 Hi Wayne,

Thanks for that reply. I am surprised, shocked even 

I have observed some other DPF systems and they do not put the crap back into the sump. I have read some negative stories about the American systems, now I see why.

Keep changing that oil ! Perhaps look at that return pipe and valve. It could easily fail out on the bad roads if you were lucky

Jaahn