I use full synthetic Valvoline and change it at recommended 10k (I thought synthetic oil was recommended somewhere in the manual, can't remember for sure). During 10k I add quart a few times as car drinks it to keep oil level closer to 'max'.

 

Generally, you won't see a manufacturer recommending a specific type of oil. What they do is recommend a viscosity, and specifications, for example SJ, that the oil must meet. Sometimes they create a more stringent spec of their own, like VW/Audi 503. It might be that only a synthetic could meet that spec.

As long as the oil meets the spec in the Jaguar manual, and you change it before it is due, you are fine.

However I do think that the improved properties of a semi or full synthetic might have advantages. The improved properties of interest to us are better performance at high temperatures, and longer life (meaning viscosity will stay within spec for longer).

Some of the dino 5w30s out there are not very good. Remember the VW sludging disaster in the 1.8T? This was due to US VW dealers using low quality oil combined with longer changes.

I certainly would NEVER let the likes of Quicky Lube near my car. Do it yourself and spend the savings on better oil.

 

If there was "sludge" in the engine, then it was not properly maintained before your friend changed the oil, proper service intervals and a good quality oil prevent sludge from forming in an engine.

Personally, I think the stories about problems going from regular to synthetic are urban myth caused by poor maintenance or someone looking for something to blame for their new oil related problem, usually leaks, I have never herd the "sludge loosening" version before. Why would synthetic loosen sludge more than regular oil?

This is why these discussions of oil get heated: Everyone "knows from personal experience' about some disaster that is going to happen if you use brand x or type y oil.

The "correct" oil is not going to make your abused and neglected 180K mile car that you bought used new again.

There is no magic here, or one correct answer just some strong personal loyalties based on years of use with no significant problems.

Buy a good quality oil and filter and change it regularly and you should be OK, but don't look for miracles or disasters caused by a particular brand or type of engine oil, it is usually something else that caused your seat heaters to stop working, not your choice of oil.

Oh and don't get started on oil additives or snake oil as I like to call them.
Vector

 

The problem is that these theoretical benefits do not translate into real world improvements. The advantages of synthetics at elevated temperatures never come into play as they represent a range that the engines never see.

Conventional oils hold their viscosity and other properties well beyond the change interval recommended by the OEM.

There's little point using synthetics unless an extended change interval is chosen.

 

Simple enough question I thought.. Oils have improved since 1998 and if you had the manual there may be a better option now of what was recommended then.(16 years ago)
In the main you have your answer,5w 30 full synthetic. It's what I use and if it's a few $$$s more I don't care.

I do use a genuine oil filter too.

 

They might not appear to, but it would be hard to to determine whether there are real world improvements or not, without a statistically sound study involving multiple vehicles (1000s of them). So on what do you base your claim that there are no benefits? Do you have data to back this up?

I have no data either, but I do have some logic. An oil with better lubricity, more detergent, better flow at low temperatures, better properties at high temperatures, and a longer life, might be expected to reduce engine wear.

A typical synthetic will have significantly better high shear rate viscosity at 150C, which is a temperature the engine most definitely DOES see, in places. It also flows better at low temperatures.

Finally, your post treats even all conventional oils as being of equal quality. ALL conventional oils hold their viscosity way beyond the service interval? Seriously? Even the cheap own brand stuff from Wal Mart? I'll say this : Shell Rotella T conventional is a MUCH better oil than some of the cheap oils out there. At least use a GOOD conventional, if you're going to cheap out.

 

Synthetics have been commonly available since the 70s. Not even the manufacturers of these oils have been able to come up with conclusive hard data to prove that engines last longer, .etc, nor has any independent agency. I've been tracking it since the 80s and can do no better than they can.

Engines rarely fail/wear out due to lubrication issues in the first place and I can't think of any that would have been 'saved' by synthetics.

If a given oil meets a spec, it meets a spec. Assuming that Walmart oils fall below the spec or that the spec must be exceeded to meet the spec is a slippery slope. Pun intended. There's no evidence that store brand oils (relabelled containers made by main stream manufacturers) are any worse than the higher priced name brands. Lots of conjecture, no proof.

As always, there will be no consensus on the issue no matter what the viewpoint or logic is. Owners should use whatever oil makes them the happiest, the cars couldn't care less.

 

Liqui Moly Synthoil Race Tech GT1 10W-60

 

Your thesis is that there is no relationship between engine wear and lifetime, and the quality of the oil that is lubricating it. To anyone with any kind of engineering background, this is totally counter-intuitive.

If any oil is good enough, why then do some manufacturers feel the need to create their own more demanding specifications?

Interestingly, the only oil recommended by Jaguar right now for new vehicles is Castrol Edge, a fully synthetic : Jaguar and Castrol Partnership - Co-engineering Quality Oil

I quote from Jaguar : "By preventing oil film breakdown friction is reduced which helps maximize engine performance. Up to 45 percent stronger* than the major competitor in reducing metal to metal contact, it’s always ready to deliver the high levels of performance demanded by Jaguar drivers."

 

Very good choice!
If my new engine is ready, i will also use a 10W-60.

 

No, the thesis is that vehicles wear out, get wrecked, get abandoned, etc. long before the engines fail from lubrication issues.

No one said 'any oil'. It's 'any oil that meets the OEM's spec'.

Big difference.

You seem to be promoting a correlation between using an oil that exceeds the spec (in some undisclosed manner) and seeing extended engine life. Nice theory, let's see some proof.

But we're not talking about 'right now for new vehicles'.

 

I see, so I should use a cheap oil and pray that I have a nasty accident before the engine wears out? I think I have a better plan.

Ahhh, so now your thesis is that in a new engine, a full synthetic will reduce wear and optimise performance. But in my older XJR, it will have no such effect. Perhaps you could explain the difference between the 2002 XJR and 2014 XJR that means the latter benefits from a synthetic, while the former does not.

NB : The 2014 Jaguar XJR has 100 bhp per litre from its 5L AJ-V8 gen III. My XJR has 92.5 bhp per litre from its 4L AJ-V8 gen II. On the face of it, they seem quite similar.

 

Making a switch from conventional to synthetic can shake sludge loose because synthetics have a lot more detergents in them. And conventional oils, just by dint of coming out of the ground and having to be filtered, have a lot more trace amounts of extraneous compounds that form sludge than synthetics that are simply not formed with those compounds in the first place.

And some conventional oils are definitely worse than others just by where they come from in the world. Pennzoil and Castrol have had issues in the past from using Pennsylvania sourced oil that naturally had more sulfur content than oil extracted elsewhere. Synthetics have a far more uniform and controllable composition.

And synthetic oil has very quantifiably better performance at all temperatures, a far more stable viscosity curve over time (far less change in viscosity curve over time as compared to conventionals, which is why they can be used longer), and far better base adhesion rates, meaning that they really do coat parts more evenly and for longer, always a good thing.

Synthetics really are superior in every regard. The question is do you need these gains? In any fairly high stress/boosted engine where you're seeing much higher heat loads at certain points in the engine and higher engine speeds, I say yes, definitely worth the marginal extra outlay, especially considering the longer usable lifespan helps defray the cost. In your average people pusher, not necessary at all IMO. It's why the girlfriends Fusion gets Valvoline conventional and my XJR gets Mobil 1. I figure in any case its maybe an extra ~$80 a year to use Mobil 1 in place of quality conventional, so even if I'm never using the extra capability it's good cheap peace of mind.

 

As stated above, consensus will never be reached. Maybe some day this principal will be universally known to the point that people know better than to bring it up again for another thrashing.

 

Since this is about the X308, I will point this out for the umpteenth time:

The specification is API SJ of suitable viscosity. What that viscosity happens
to be is a matter of interpretation of the illustration below the grade specification.

The oft quoted "Jaguar recommends Castrol 5W30" is qualified by the
closing phrase "for best fuel economy. This is more related to CAFE
regulations than any real world benefit to the owner.

Anyone who understands plain english can understand that "for best fuel economy"
is orthogonal to "for best engine longevity".

The Mexican market had a special warranty stipulation of 10W40 minimum viscosity.

Obviously, Jaguar did not care for the actuarial odds on warranty engine replacements
if an owner used a thinner oil in a hotter environment. Owners in states such as TX, NM,
NV, AZ, FL, CA might want to think twice even though that restriction was never
applicable to US markets.

Long oil change intervals may or may not be influenced by the total cost of
marketing a vehicle with "maintenance included".

Jaguar's bread is buttered with best fuel economy for CAFE reasons, EPA mileage
ratings, and marketing to a crowd in favour of carefree maintenance included
ownership or leasing.

As long as not too many engines blow up within warranty coverage, they care
not how many engines blow up, and indeed benefit from after warranty parts
and service work.

Currently running Shell Rotella 0W40 which didn't make a whit of difference down to -30*,
therefore switching back to Shell Rotella 15W40 which the engine likes better in warmer
weather.

++

 

Vector, Mikey, I see your point: this crap never ends!

 

"Making a switch from conventional to synthetic can shake sludge loose because synthetics have a lot more detergents in them"

This is a myth. There are conventional oils with various levels of detergent, and synthetic with various levels of detergent, dependent on the application.

 

Right. I have seen these go on for page after page with lots of wild assumptions with no basis in fact.

Plums tried to make a some good points about Jaguar's real reasons for their specification, I hope some of the guys read his and my comments before posting some more questionable "facts" about a particular brand or type of oil.

But they won't.

We all have our loyalties to particular brands or have come to believe this or that about a certain product, but the oil discussion seems to bring out the most fervent defenders and detractors.

Vector

 

And the OP frequently ends up going away more confused than when he started.

 

Over what length of service, and reduce by how much?

And under what kind of real-world use and ownership does the reduced wear, if it can be measured, become seriously worth considering?

Any of us can very easily find examples of engines with 200k+ miles or more that run as sweet as can be with no attention to oil spec whatsoever. Go to any wrecking yard, or car repair shop, or even your next door neighbor. Such cars are ubiquitous. Heck, even in my own extended family there are cars with 200k-250k miles with sweet running engines showing no signs of impending doom...and I can positively assure you that the owners are more concerned about what type of pancake syrup they buy than what kind of engine oil they use. In fact, one of them has been serviced almost exclusively at Walmart for almost its entire life!.

At this point we'd have a very difficult time convincing the owners that they should be much more pensive about selecting engine oil....as there is no harm in being nonchalant on the subject.



Are there any BAD oils out there? One that have been shown to be so sub-par in quality that engine wear is obviously, measurably, and undeniably accelerated....or are known to cause engine damage outright? If so, please identify which !

In the end, however, I'll join in with the others who claim the best answer is to simply use whatever makes you feel best

Cheers
DD