fully synthetic oil

[brightspark]

whats the recomended oil change millage on fully synthetic oil on cars these days anyone /? tnx

 

[tigler]

Depends on the make and model. Change intervals depend on many factors. Synthetics resist breakdown for much longer than minerals but filtration is a major factor as is the type of use.

 

[brightspark]

Depends on the make and model. Change intervals depend on many factors. Synthetics resist breakdown for much longer than minerals but filtration is a major factor as is the type of use.

vauxhall combo diesel works van and it gets a lot of hard use times money edit it never goes over 70mph i have heard they do 110 mph mind

 

[tigler]

If it's common rail and does mainly long journies it may be ok to get 12-18 K miles out of a high quality, fully synth. The best way to find out how far the oil will go is to get a sample analysis every 5K miles, that will reveal what is happening to it, showing things like fuel contamination, debris accumulation, breakdown of various additives, metal deposits, etc, etc. The lab can then recommend how often to change oil.
The thing to be careful of with a turbo diesel is debris accumulation, turbo's don't like dirty oil.

 

[octo0072000]

oil and filter every 6 months then

 

[stormin]

When I bought my new Octavia Tdi in 2007 the variable servicing said upto 30,000 miles between oil changes

Being more wary I opted to have services every 10,000 and the synthetic oil was supposedly changed at these intervals by the main dealer. Low and behold at 70,000 miles and just over three years old, catastrophic engine damage due to a hydraulic tappet wearing through and trashing the cylinder head.

No way I would ever go beyond 10,000 with oil changes on a diesel engine regardless of how good the oil is. And from now on I will revert to doing all oil changes myself so I know for sure it has been done.

Some engines have better filtration systems, the Land Rover Td5 I had springs to mind, with it's centrifugal pre filter and I believe these engines can go on to large mileages other faults aside.

 

[octo0072000]

When I bought my new Octavia Tdi in 2007 the variable servicing said upto 30,000 miles between oil changes

Being more wary I opted to have services every 10,000 and the synthetic oil was supposedly changed at these intervals by the main dealer. Low and behold at 70,000 miles and just over three years old, catastrophic engine damage due to a hydraulic tappet wearing through and trashing the cylinder head.

No way I would ever go beyond 10,000 with oil changes on a diesel engine regardless of how good the oil is. And from now on I will revert to doing all oil changes myself so I know for sure it has been done.

Some engines have better filtration systems, the Land Rover Td5 I had springs to mind, with it's centrifugal pre filter and I believe these engines can go on to large mileages other faults aside.

the octavia and vag group have known problems with the PD diesel engine
it uses a specific oil most people ignore this mainly taxi drivers in the end it wears the lobes off the injector pump cams ends up on three cylinders and kills the head cam etc

 

[MattF]

oil and filter every 6 months then

That's the type of thinking I always stick with. Every 6 months or 5000 miles, whichever comes first was what I was always taught, (I actually change mine every 5000km's, but what the hell ).

With regards synthetic and diesels, it's the soot and other crap diesels generate which is the problem causer. It doesn't matter how good an oil you use. The engine is still going to be chucking the same amount of crap into it, and the filter is still going to be filtering as much of that crap out. Change often is always the best option. It can only have either a neutral or beneficial effect on the engine, and with the amount of times manufacturers have had unexpected problems with certain engines due to their blind faith in their new 'magical properties' oil, I'd be inclined to stick with the old rule of thumb personally.

 

[Shox Dr]

Whether it's true or not. I was once told Oil doesn't lose it's properties it gains them.

In that it collects all the crap in the engine, and holds it, for the filter to filter it out.

So it matters not what you put in the motor, it's how you look after it.

My Bikes are serviced every 2k and Cars 5k.

 

[shenion]

I used AmsOil synthetic in my cars and bikes. Said right on the bottle good for 45,000 miles or 1 year. They have process for truckers that they can go 100,000 miles with no oil change (has special filtering.)

On cars/bikes, you needed to use their 5-micron filters and change it twice a year (twice as often as changing oil.)

 

[tigler]

The actual oil, that is the oil without additives does not break down by mechanical wear. But the additives and friction modifiers do degrade and eventually become ineffective. Oil does oxidise though, that is breakdown as a result of high temperature in the presence of air. This is where synthetics exhibit their superiority, with some synthetics being almost indestructible, those with Polyol Ester base stocks being the best. Full synthetic base stocks also have an innate high viscosity index so they need almost no viscosity improver, which breaks down over time. So, if you start out with a 10w40 oil, it stays almost 10w40 over the entire life of the oil, unlike mineral oils which eventually break down to 10w as the VI's degrade with use. Also, the amount of particle suspension the oil can carry before it saturates and begins to cause engine damage is limited. Thats where filtration becomes crucial. Filters vary in the smallest particle size they can remove from the oil, known as micron limit. Some are quite inferior in this respect. Aftermarket filters are available that remove much smaller particles than even the OEM spec filter. So, theoretically, with a filter that removes a very small micron particle size, by changing the filter every say 7.5 k miles, a high quality full synthetic could go on for 30k miles or more.
The only way to optimise the use of the oil though, is to have a routine analysis every so often, to monitor oil pollution and degradation. That may not be cost effective for a normal, run of the mill vehicle though. It is standard practice for large commercial and plant though, where oil quantity can be measured in many gallons and to determine when an engine overhaul is required.
So the pragmatic, 6k mile oil change interval makes sense on a family car !

 

[brightspark]

i thought the general idea of using synthetic oil was that it lasted longer between oil changes

 

[tigler]

It can but is still prone to the issues mentioned above.

 

[madkayaker]

My dad always said oil is cheep engine rebuilds are not. Probily not much science in it but he had many big fast bikes in the 70 and 80

 

[TAITSIE]

the octavia and vag group have known problems with the PD diesel engine
it uses a specific oil most people ignore this mainly taxi drivers in the end it wears the lobes off the injector pump cams ends up on three cylinders and kills the head cam etc

I work in a motor factors and its a problem trying to convince people that they need a certain type of oil, they think we are just trying to get them to buy the top grade oil.
Taxi drivers are amongst the worst but they should know better.
If someone chooses to ignore our advice and put cheaper oil in then its their problem

 

[tigler]

My dad always said oil is cheep engine rebuilds are not. Probily not much science in it but he had many big fast bikes in the 70 and 80

Difficult to argue against that strategy. I use probably the best synthetic oil there is in my Evo but I still change it at 4500 miles, as per factory recommendation ! The engine cost me plenty and it simply isn't worth the saving in oil by say doubling the oil change interval by the potential risk to it.
So basically I'm using that quality of oil as insurance.
Conversely, with my daily driver, 198,000 miles and counting, Xantia HDi, I use Morris 10w40 semi synth at £12 per 5ltr in bulk 25 ltr drums, changed every 6-7000 miles. Being doing that for 6 years and 110,000 miles and it still doesn't use any oil to speak of between changes, and the oil feels and smells fine when it is changed.

 

[Lawnmowerboy]

Is it true you have to change oil more often on carbed engines than efi?

 

[tigler]

Well, oil change intervals have become longer with electronic managed, fuel injection engines, same with common rail diesel, reason is less fuel contamination in the oil than happened with carbed and mechanical injection engines.

 

[stormin]

I work in a motor factors and its a problem trying to convince people that they need a certain type of oil, they think we are just trying to get them to buy the top grade oil.
Taxi drivers are amongst the worst but they should know better.
If someone chooses to ignore our advice and put cheaper oil in then its their problem

I would say the problem with the PD engines is in the Camshaft. The fact that it needs to use huge lobes for the injectors leaves only room for narrow lobes for the valve tappets. Some engines were fitted with hardened tappets apparently and some not, hence the excessive wear.
I think VW realised this and hence the 2.0 Tdi's were twin cam I believe, and later went to common rail rather than unit injector PD.

 

[TAITSIE]

A lot of people insist on putting cheap 10/40 semi synthetic or even mineral oil in these engines because its cheaper, they will not pay a few pounds more for the correct oil even though we tell them it will damage the engine
We also sell a lot of camshafts, cam bearings and followers to taxi owners