V6 which OIL

[stusV6]

Which way to go?

The car may be used for the occasional track day soooooo.........

Do I go for Elf Excellium LDX or the Silkolene Pro S

Both are fully synthetic 5W40 although the Excellium LDX is a PAO oil and the Silkolene Pro S is an Ester/PAO!

The Excellium LDX is £101 for 48lts and the Silkolene Pro S is £109 for 20lts

What do we think guys?

Cheers Stuart


[Edited by stusV6 on 16 October 2004 at 5:31pm]

 

[John V6]

Excellium LDX and change twice as often.

 

[stusV6]

Cheers John........................seen as how there isnt many of us Im bumping it to let everyone see it eh

Cya Stu

 

[John V6]

As long as you have a good oil no problem.

V6 is not a highly stressed engine by any stroke of the imagination.

 

[oilman]

Check first that its not a PAO blend as we could be comparing apples and pears here.

I would doubt its 100% PAO as its way too cheap. Just make sure before you buy as Id say it contains a percentage of PAO (up to 20%) and not like the Silkolene which is 100% PAO/Ester blend.

If they wont confirm the contents, buyer beware, another oil labelled synthetic that isnt!

Cheers

Simon

 

[stusV6]

Simon what does PAO actually mean?

Cheers Stu

 

[oilman]

Its one of three proper synthetics used as oils (these are not petroleum refined or derived) and are far superior to petroleum based lubricants.

They are PAO (Poly alpha olefins), diesters and polyolesters.

Cheap oils (under £5.00 per litre) labelled as synthetic are usually "hydrocracked" mineral (petroleum derived) oils and are not the real thing.

The following cleary describes this synthetics issue:

A word of caution – You get what you pay for!



Below is an article written by John Rowland, Silkolene/Fuchs Chief R & D Chemist for 40 years.



Quote:



Costs of synthetics vary considerably. The most expensive are the “Ester” types originally only used in jet engines. These cost 6 to 10 times more than high quality mineral oils.



The cheapest synthetics are not really synthetic at all, from a chemists point of view. These are in fact specially refined light viscosity mineral oils known as “hydrocracked”. These have some advantages over equivalent mineral oils, particularly in lower viscosity motor oils such as 5w-30 or other oils with a low “W” rating such as 5w-50 etc and they cost about 1.5 times more than good quality mineral fractions.



We use several different grades of this base oil, where appropriate. This is the “synthetic” which is always used in cheap oils that are labelled “synthetic”. Yes it’s a cruel world, you get what you pay for!



Now, you may ask, why are these special mineral oils called “synthetic”?



Well, it was all sorted in a legal battle that took place in the USA about ten years ago. Sound reasons (including evidence from a Nobel Prize winning chemist) were disregarded and the final ruling was that certain mineral bases that had undergone extra chemical treatments could be called “synthetic”.



Needless to say, the marketing executives wet their knickers with pure delight! They realised that this meant, and still does, that the critical buzz-word “synthetic” could be printed on a can of cheap oil provided that the contents included a few percent of “hydrocracked” mineral oil, at a cost of quite literally a few pence.



So, the chemistry of “synthetics” is complex and so is the politics!



The economics are very simple. If you like the look of a smart well-marketed can with “synthetic” printed on it, fair enough, it will not cost you a lot; and now you know why this is the case. But, if you drive a high performance car, and you intend to keep it for several years, and maybe do the odd “track day”, then you need a genuine Ester/PAO (Poly Alpha Olefin) synthetic oil.



This oil costs more money to buy, because it costs us a lot of money to make, very simply, you always get what you pay for!



Unquote:



Sad but true, like everything in life - Buyer Beware!



Cheers

Simon




[Edited by oilman on 19 October 2004 at 10:05am]

 

[stusV6]

OK guys this is the last time Ill be on about this..................just have one more question then we BUY BUY BUY

Rite here goes..................my car has been service every year since new (3years old 3services).......................lets assume that when the car was new it had Elf Excellium LDX in...................at the first service they put in Mobil 1..........at the second they put in Elf Excellium LDX and the 3rd they put in Mobil 1 again.

Now if these oils are NOT as stated on the box ie 100% fully synthetic.....................but nearer 70/30 or 80/20 (mineral/synthetic).

The question is if I now fill it with an oil which IS 100% fully synthetic and given this will be thinner oil than the others is it possible that I could induce oil leaks?

Again this WILL be the last time I post on this thread

Cheers Stuart

 

[oilman]

Stu,

You missed the point mate Im afraid.

A synthetic 10w-40 is the same viscosity (thickness) as a mineral or semi-synthetic 10w-40, its just a better oil.

Do not confuse "basestocks" used i.e. synthetic or petroleum with the thickness of the oil, this is called viscosity.

Have a read of this and it explains viscosity:

What is this thing called viscosity?



It’s written on every can of oil and it’s the most important visible characteristic of an oil.



The viscosity of an oil tells you how it reacts in certain circumstances and how it performs as a lubricant.



When a oil is subjected to external forces, it resists flow due to internal molecular friction and viscosity is the measure of that internal friction. Viscosity is also commonly referred to as the measurement of the oils resistance to flow.



There are two methods of viewing an oils resistance to flow. Firstly there is Kinematic Viscosity which is expressed as units indicating the flow of volume over a period of time and this is measured in centistokes (cSt).

An oils viscosity can also be viewed by measured resistance. This is known as Apparent Viscosity and it is measured in centipoises (cP).



However in the real world an oils viscosity is also referred to in such terms as thin, light and low etc. This suggests that the oil flows or circulates more easily. Conversly, terms such as heavy and high etc suggest the fluid has a stronger resistance to flow.



The reason for viscosity being so important is because it is directly related to the oils load-carrying ability - The greater an oils viscosity, the greater the loads that it can withstand. (It must be added when new not over a period of time as all oils “shear down” with use)



An oil must be capable of separating the moving parts in your engine at the operating temperature. On the basis that an oils viscosity is related to its load carrying ability, you could be fooled into thinking that “thicker” oils are better at lubricating but, you’d be wrong in this assumption. The fact is that in the wrong application a high viscosity oil can be just as damaging as using a low viscosity oil.



The use of an oil that’s too “thin” can cause metal-to-metal contact, poor sealing and increased oil consumption and conversely, an oil that’s too “thick” can cause increased friction, reduced energy efficiency, higher operating temperatures, and poor cold starts in cold temperatures.



It is very important that you select the correct oil, not too “light” or too “heavy” and your Owners Handbook is a very good place to start as it lists the temperatures and options.



Oils thicken at low temperatures and thin as the temperature increases. The actual rate of change is indicated by their viscosity index (this number normally listed on the oils technical data sheet indicates the degree of change in viscosity of an oil within a temperature range, currently 40-100 degrees centigrade)



An oil with a high viscosity index, will normally behave similarly at these two temperatures but an oil with a low viscosity index will behave quite differently. It will become very fluid, thin and pour easily at high temperatures. A higher index is better!



Multi-grade oils are designed to perform at high and low temperatures by adding polymers to a base oil (5w,10w, 15w etc) which are heat sensitive and “uncoil” to maintain the higher viscosity sae 30,40,50 etc. This means that the oil can be used “all year round” rather than using different oils for summer and winter.



It is important to understand that the selection of the correct oil for your car is not just guesswork, you must consider the temperatures at which you need the oil to operate a 0w, 5w oil is better for cold starts as the oil circulates more easily when it’s cold and is able to flow around the engine more easily and quickly, offering protection at the

critical moments following cold engine start-up. These oils are also known to give better fuel economy and engine performance.



Finally, all oils “shear” or thin down with use and this means that an oil that started life as a 10w-40 will with use become a 10w-20. The period of time this takes depends on the type and quality of the oil. The most “shear stable” oils are proper Synthetics, either PAO (Poly Alph Olefins) or Esters which have very high thermal stability. They are in general of the more expensive variety but last longer and give the best levels of protection.


Hope this helps to explain the meaning of viscosity.

Cheers

Simon