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The difference in time that the two oils take to get to the timing chains (upon start up) will have a less than negligible difference to the wear in said timing chains issues..

There is no oil on this planet that will completely drain to the bottom of the sump.. even over a prolonged period...

There will always be a slight amount left on surfaces.. no matter how small.. and it makes the difference between a dry surface or not in terms of lubrication...



Stop searching the interweb for ways of having a problem that you don't have... ;)
 
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I came across this interesting article and it made me think of this thread. Could Jaguar changing the required oil from 5W20 to 0W20 have anything to do with the timing chain issues in that the lower viscosity oil gets to the hydraulic tensioner quicker at startup?

http://www.agcoauto.com/content/news/p2_articleid/339
I have read that this is the exact reason for the change.
But before that I read it was to eke out an extra mpg or two on the CAFE and EU fuel economy lab tests.
As Pete says it makes SFA difference 99.99% of the time and it's only at ambient temps below around 20 F (in other words really fecking cold) that it helps with lubrication of the timing chains and tensioners.
One reason I have never put 0W-20 and only ever put 5W-20 in my XFR and F-Type - it never gets anywhere near that cold here.
 

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I have read that this is the exact reason for the change.
But before that I read it was to eke out an extra mpg or two on the CAFE and EU fuel economy lab tests.
As Pete says it makes SFA difference 99.99% of the time and it's only at ambient temps below around 20 F (in other words really fecking cold) that it helps with lubrication of the timing chains and tensioners.
One reason I have never put 0W-20 and only ever put 5W-20 in my XFR and F-Type - it never gets anywhere near that cold here.

I appreciate that 0W20 can go down to a lower temperature than 5W20 and these minimum temperatures in the region of -30°C and lower are extreme and likely never to be of concern to most and their climates. However, is the whole viscosity range not respective to temperature for each grade oil? For example, at say 5°C will the 5W20 not be more viscous than the 0W20?
 

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The difference in time that the two oils take to get to the timing chains (upon start up) will have a less than negligible difference to the wear in said timing chains issues..

There is no oil on this planet that will completely drain to the bottom of the sump.. even over a prolonged period...

There will always be a slight amount left on surfaces.. no matter how small.. and it makes the difference between a dry surface or not in terms of lubrication...



Stop searching the interweb for ways of having a problem that you don't have... ;)

I'm not sure I get the point of your last sentence. Anyway, the part of the article which caught my attention wasn't about lubricating but about the hydraulic tensioner:

"Another source of timing chain problems is oil of the wrong viscosity or specifications. A lower viscosity oil will flow faster than a heavier oil, especially when cold. Engine designers specify lower viscosity oil to promote quicker flow. Many engines with timing chains now specify 0W20 oil viscosity. Quickly pressurizing the hydraulic tensioner keeps the chain tight and reduces guide breakage."
 

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I remember, back in the 60's when I had Mk 2 Jags, the problem was high oil consumption - say 300 miles per pint.
The usual solution was to use Duckhams Q , a very thick oil which at least halved the consumption.
 

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Today's modern engines consume little or no oil, I know my XFR and F-Type have never once needed a top up between oil changes.
My guess is it's mainly due to much smaller tolerances especially piston ring gaps such that bugger all oil gets past the rings and gets burnt off.
 

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Here's a thought:

If the oil galleries are full to begin with, what viscosity oil is used makes not a jot of difference, i.e. none whatsoever, to how long before the chain tensioner "sees" pressure from the pump (and hence takes up any slack). It is stopping "drainback" that is important.

And the case for guides being damaged in the event of the tensioner taking a second or so to extend is flimsy at best anyway. There isn't, or should not be, that much slack anyway, certainly not enough for chains to "flail" around in a normal engine. If they do there are other problems, like severely stretched chains.
 

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Here's a thought:

If the oil galleries are full to begin with, what viscosity oil is used makes not a jot of difference, i.e. none whatsoever, to how long before the chain tensioner "sees" pressure from the pump (and hence takes up any slack). It is stopping "drainback" that is important.

And the case for guides being damaged in the event of the tensioner taking a second or so to extend is flimsy at best anyway. There isn't, or should not be, that much slack anyway, certainly not enough for chains to "flail" around in a normal engine. If they do there are other problems, like severely stretched chains.

Aye I saw that bit about the non-return valve and did wonder, I'm trying to get a better understanding as to what these articles are all about with regard to viscosity and the hydraulic tensioners. I was also thinking, isn't there a ratchet mechanism in place anyway to maintain tension? So what is it that's causing the failures, is it just general wear or poor component quality or insufficient spec or something?
 

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Today's modern engines consume little or no oil, I know my XFR and F-Type have never once needed a top up between oil changes.
My guess is it's mainly due to much smaller tolerances especially piston ring gaps such that bugger all oil gets past the rings and gets burnt off.
Can you have a word with my engine please. Got through a litre of 5W-20 every 3.5k miles! Has reduced since being filled with 0W-20 somewhat, only needed a 500ml top up after 4k
 

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Aye I saw that bit about the non-return valve and did wonder, I'm trying to get a better understanding as to what these articles are all about with regard to viscosity and the hydraulic tensioners. I was also thinking, isn't there a ratchet mechanism in place anyway to maintain tension? So what is it that's causing the failures, is it just general wear or poor component quality or insufficient spec or something?
Believe it or not, the Stag does have a ratchet system on the timing chain hydraulic tensioners. Simple mechanism.

One cause of wear on the Jag engine is the fact that the steel piston of the hydraulic tensioners pressed against the soft aluminium of the guide backing, and wore a "hole" in that, thus losing its full range of adjustment.
Bearing in mind that the 4.0l V8 had tensioner issues that took 3 or 4 updates to cure (the 4.2 was finally sorted I believe), I am surprised that the newer 5.0 V8 has too, very poor design work IMHO.
 

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Here's a thought:

If the oil galleries are full to begin with, what viscosity oil is used makes not a jot of difference, i.e. none whatsoever, to how long before the chain tensioner "sees" pressure from the pump (and hence takes up any slack). It is stopping "drainback" that is important.

And the case for guides being damaged in the event of the tensioner taking a second or so to extend is flimsy at best anyway. There isn't, or should not be, that much slack anyway, certainly not enough for chains to "flail" around in a normal engine. If they do there are other problems, like severely stretched chains.
Good point - but thats on the basis that the oil galleries within the block are all free.

This happened not a Jag, but a Toyota Avensis 1800cc engine that my Ex had.

She over-filled it at one point - and I ended up sucking some of the oil out with small bore pipe and a hand pump to the correct level.

Within a year - we were travelling to the ferry from Scotland and the cars engine gave up - literally.

The oil level was fine - as was the pump - but the engine had still managed to weld itself through lack of lubrication.

The car was out of warranty - and I had to source a new or used engine. A used engine was sourced from Dragon Engines in Chesterfield - very good company btw.

Chatting to the guy I was dealing with - he told me that that particular engine was known for hotspots - and the oil would end up getting brunt in one place of the block that it would carbonise, and over time - this line was blocked,


I'm wondering if Toyota are the only ones who have had this problem. I'm not trying to say Jag has the same issue - but maybe it should be taken into account.

As for the tensioners - they are hydraulically operated we all know that. So in theory - the pressure transfer should be instantaneous - but only once pressure has been reached.

How many revolutions does the engine do before the correct pressure is fed to the tensioner?
 

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My MY11 XFR had 5W-20W on the filler cap, but my MY15 XFR shows 0W-20W on the filler. I believe it was part of their attempt to reduce emissions and EU consumption figures.

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I've always used 5w20 in my 2010 XFR but have thought about using 0w20 next time. I genuinely can't work out what's safest/best for the engine. I do change it every 6k though.
 
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