There is SO much discussion and "information" out there regarding engine oils (and filters) that it is really overwhelming. Doubly so for someone like me with no technical, engineering, or scientific knowledge. I say "information", in quotes, as an acknowledgment (or is it an assertion?) that a lot of stuff floating around out there might not be completely accurate or honest. Or, for many, the information might not even be useful or applicable to their circumstances.

It's somewhat akin to "The tyranny of choice".

And IMO doesn't need to be known in order to successfully maintain and enjoy our cars.

Anyhow, there are many ways to enjoy the car hobby and many aspects to being a car hobbyist. "Care and feeding" is part of the enjoyment for many and may it ever be thus.

Having used old Jags as daily drivers for over 25 years (and by now probably 400k miles) I've taken enjoyment from learning that they're not quite as mysterious, temperamental, and needy as I was led to believe many years ago.

Putting them on a gourmet diet isn't really required although a person can glean enjoyment from doing so.

And it's all about enjoyment !

Cheers
DD

 

But it is known, its right in the owners manual.

what am i missing here?

 

With you Doug.

Coffee #5 and its 3PM.

As an Engine Reconditioning Machinist from the 60's, I have seen a few??? changes.

I run the flag of "Good Oil, Changed Regularly inc filter (if it has one), and let it be.

The V12 is a 1954 design, and 1963 1st install (MK X), and oils then were a tad different to now.

One of my Pre HE is at 875000kms, the other at 460K, the Red HE is 410K, The Blue NO IDEA, the odometer stop 15 years ago, but shiiit loads I reckon. One of the kids canes that sucker as a D Driver.

They are untouched from when they left Coventry, except the Red HE, I was bored, it leaked oil, so I refreshed it.

Oil and filter at Approx 5K kms, and never ever start that engine and then stop it before it gets o operating temp.

Brands matter nit, NOW, and usual;y whatever is on special will do the job.

As Ben mentioned, STRETCH the legs, OFTEN, and where I live that is more than doable.

I do understand the "fuel efficiency" of this new Gen garbage, dont agree, but thats allowed. The Big Beast being a 5.7 Hemi, uses the same fuel amount as the V12's, so my brain is trained, and at 76 that is a good thing, HA.

 

Nick
The owner's manual recommendations will be fine, obviously. No V12 used on the roads has ever failed because the owner's manual oil recommendations were not followed. In fact, very few if any V12s used on the roads and properly maintained have ever failed for mechanical reasons. Grant's post above shows what huge mileages they can rack up with no mechanical problems.

My point is that it is quite possible to improve on the owner's manual recommendations for the reasons many here, eg BenKenobi, have so clearly explained. Now whether such improvements are actually needed is another question, and they probably are not (as Doug so amusingly posts); but I prefer to use the best possible lubricant, even if an adequate one would do the job. Nothing in the manual to suggest that this is a bad plan. After all, in the early 1980s TWR raced V12s and they considered that the (then) new synthetic oil they used, made by Motul in France, enabled their engines to last an entire long race because of the oil's superior heat tolerance.

To enlarge the 'why not improve if you can' point, I have made a few improvements to my car in other areas, for instance an aluminium radiator reducing front end overhang-weight improves ride and cornering turn-in; I have simplified the cooling bleed system which was always a desperate compromise on the V12 XJS, caused by styling considerations; I have a modern Torsen diff and higher quality UJs in the rear axle; I have relocated the Lucas amp to a cooler place; and fitted electric fans.

None of these are essential, but for me they make the car perform better and/or improve reliabilty and ease maintenance. I believe using more modern, better performing oils is a similar thing, not essential but nice to know you have.

 

All,

Thank you so much for all your thoughts! I know that this has been referenced very often in other threads, so I guessed that there may be quite a debate! I'm grateful for all the feedback and the polite manner in which everyone has shared quite differing personal views without any unpleasantness.

I think that the key sentiments I can take from this, many of which we we already appreciated, are:

- We all take a different view to the maintenance and use of our cars, varying from efficient maintenance to indulgent pampering
- The original oils available and Jaguar recommendations have stood many owners in good stead, enabling the V12 to often reach very high mileages before rebuilds are necessary
- Advances in technology enable owners to benefit even further, if they wish, from the use of modern oils and better understanding of oil and engine interaction
- Regular, and frequent, oil changes are perhaps more important than grade or manufacturer nuances
- Additional additives are a personal choice with views both and for and against their use with modern synthetic oil additive packages
- Modern road conditions are not necessarily conducive to the engines being able to operate in an optimal manner
- Oil is cheap, engines are expensive


Taking into account, everything that's been shared, I have decided that I'll probably put a good quality 5W40 or 10W40 oil in the car, with confidence that it will do no harm!

Thank you all again for your input. At the risk of further inflaming the community, I quite like the idea of discussions on Oil additives or Fuel brands? Or should I just get my coat and leave...?!

Cheers

Paul

 

On the topics touched on I find one internet source that I half trust - John Cadogan - Australian fella and an engineer - not a fake youtube engineer but a bona fide real one, sure he has his bias's as we all do but he does put some effort into dispelling and challenging the vast amoung of internet myth that we are bombarded with - just two are below - fuel is problematic because it is so varied in different regions - we all have our own bias's including this fella but he sets out to back up every statement with facts that can be verified - I wound't trust anything that is done as a result of sponsorship so beware.

In the business we call it data smog, there is so much information out there that the 'truth' can be really obscure and require a lot of digging, even then it is down to what 'we' believe. End of the day whilst the grade is important how the car is used, how often oil is changed matter - there is way more to lubricants than 'grade' - they're engineering in themselves. I list these videos because it is put across in a 'consumable' manner - but there are many many sources, you just need to approach with the appropriate level of cynicism.

 

Dont get me wrong, i have all kinds of mods on my car as well, things I feel are improvements.

i acknowledge oils have improved over the years. I use Mobil 1 15W50 in mine(summer driven only).

I feel people get carried away the oil discussions, its easy to get dragged down the rabbit hole.

for me, i use the grade the owners manual calls for in 100% synthetic.

 

Me too, but you have to be the brave one to start it, Paul!

 

That is also very true! Most V12's are not driven hard either, that makes a difference too. As long as you use a gasoline rated oil that isn't a 0W-16 for many climates you'd probably be fine.

 

There were implicit properties about the oils of the 1970-1980's that are baked into those recommendations, many of which are no longer true. Viscosity improvers were not as good then, so the recommendation was to have a heavy oil initially and it broke down to what they really were after in short order. Now we can run a lighter oil that stays in grade and end up in the same place as and old initially heavy oil after 1000 km.

That's the reason the lower first number oils were not recommended, they broke down to something too light. They knew something lighter was better for cold start and gave less wear in the engine, but the thin oils of 50 years ago couldn't maintain the hot film strength. Synthetic oils of today can.

Rather than a 15W-50, a 0W or 5W-40 synthetic would be a better choice today.

 

I’m going to disagree with you on that claim.

 

Me too ! And I'm sure I always will.

However as the decades have rolled by I've become much more selective about where my effort and money are spent. I more often ask myself the old question "Will the juice be worth the squeeze?". And more often I'm answering "No" :-).

But that's just me.

Cheers
DD

 

All of us as we get older, Doug...

 

In temperate environments like the UK 15-40 is best, here in the American Southwest 20-50 is better due to ambient Temps
Castrol, Deli, and Rotella all make a high-zinc oil in those weight grades that are all excellent

 

Deli = Delo haha

 

As a restoration shop owner, our considerations may be slightly different than those of an enthusiast; Concern #1 is no customer complaints or comebacks.

The average used Jaguar we see is now fifty years old (Many cars from the Seventies are still with us) and have been running dinosaur-based (non-synthetic) oil
for many years; Typically a change to synthetic oil will result in several new oil leaks, so is not recommended.

As a previous well-educated poster mentioned, all oil additives are disrecommended; The short answer is that a modern, well-constructed oil will see any additive
as a contaminant and will isolate it from having any effect...This includes zinc additives, which must be "cracked in" to the formulation to have a positive effect.

There have been studies showing that a high-zinc formulation is quite unnecessary after break-in.

Apologies for adding to the confusion.

 

I use 10w40 shell Helix on my V12, because its made by a reputable company, is within spec, and is cheap enough.

I'm sure I have read however that if your primary concern is engine wear and longevity, and you don't really care about fuel economy or parasitic losses etc, you should always run the maximum thickness oil recommended by the manufacturer, because with all else being equal, thicker oil = less engine wear.
Often you see the same brand/model of engine recommend anything from say a 0w20 to a 5w40 across different markets. It may be because in one market, sales to fleets etc may depend on hitting a certain official economy figure, so they spec the 0w20, and sacrifice some engine wear.
Other markets may be less particular about fuel economy and much more about long term durability, or the local market may necessitate the manufacturer offer a longer warranty to stay competitive, so they'd spec the 5w40.
The recommendation from the engineers who are interested in the engine lasting 500k miles is often at odds with the recommendation borne out of the engineers who are interested in maximum fuel economy, or the marketing department or branding department who insist on a particular brand oil be used etc.

Basically, its a minefield

 

Asdrew
I do agree about Shell Helix being a good oil. But...
As most wear occurs in the first few mins after startup, and as there seems to be concensus on here that thinner oil is better at this point, why do you feel a 10w cold weight oil is better than a 5w?

(your quote being "because with all else being equal, thicker oil = less engine wear.")

 

That's why I always subscribe to using the lowest number in front of the 'w'.

0w40 for me is the way to go. Why there's any need for a higher number makes no sense to me.

 

Correct. That's why the recommendation from Lubrication Engineers is to use a 0W or 5W where available.