Classic cars forum & vehicle restoration.

[gillberry]

Hi all , This post was on one of my rover forums but I thought I would share the info .
" The best thing you can do when it comes to engine oil is to use a full synthetic (except when bedding in). they have a much flatter viscosity index (so they don’t go thick and hard to pump when cold, and don’t go thin and reduce protection when too hot), they always have a top quality additive package because they’re premium brands, they are far, far more resistant to breakdown on the bores, producing less contaminant and carbon products, their chemical structure actually produces less friction and they last longer in the sump.
On engines, they can double component life – in gearboxes, it can be several hundred percent life extension with quality synthetics. When you switch to synthetic in some engines it’s amazing how rarely you have to adjust the tappets – the valve stems almost stop wearing.

One top tip is that Mobil 1 is the best on the market, and the only one to be fully polymerised from C2 gas rather than hydrostabilsed from mineral base stocks. It’s the dog’s, and the stuff you buy at your local garage is exactly the same as the stuff that goes into race cars – including F1. Another top tip is to know that Halfords synthetic is re-badged Mobil 1 with a slightly different viscosity improver. Every few months they have a 2-for one offer too – so fill yer boots when they do. Mobil has led the world market in synthetics for 25 years and produces them on a scale that others cannot afford to invest in; don’t think that a ‘specialist’ manufacturer’s racing synthetic that costs £10 or more a litre is better than Mobil 1 – it’s actually nowhere near as good..

Both Mobil 1 and the Halfords brand have a slightly thicker version which suits the Rover engine better. The 0W/40 and 5W/40 are fine in more modern engines, but the Rover prefers anything from 5W/50 or 15W/50. The first figure refers to the oil’s thickness as 0 deg centigrade, and the second to its thickness at 100 deg centigrade.

The Rover was designed for thicker oil, so if you put thin synthetic in it may creep past the rings and lead to high oil consumption. Some people very wrongly say that’s because you can’t use synthetic in the Rover – in fact it’s just that they used the wrong viscosity. Use the right synthetic, and oil consumption will drop because its resistance to temperature and higher boiling point means that less is burned or evaporated off the bores when the oil film is exposed to the combusting gases. "

Hope this is of use to you all .

[gillberry]

Anoth er bit from the same guy .
"Castrol is a good little company - by coincidence, it was actually set up by a bunch of ex-Mobil employees. Good though their products are, they simply do not have the funding to make the sort of synthetic processing facilities that Mobil has or to develop their products to the same level. They have produced some very professional TV ad campaigns though – and that’s what their name has been built on.

Think of it in terms of engine development. TVR developed the AJP engine on a budget of £1.5 million. It makes power, sounds okay and looks the part, but it has loads of problems. When Ford or BMW develop an engine, they will spend 50-100 times the amount TVR can spend. Would you rather have the V8 from a Cerbera or an M5 in your SD1, nationality aside?

Some of the smaller oil companies have very successfully made their names in performance motorsports and racing, and people pay silly money for their ‘special’ synthetics. I could name them but won’t – they’ve marketed very successfully but their products are horribly overpriced and nowhere near as good as those produced by the majors.

A good example some years ago that I will name was the Duckhams green engine oil. The concept was borne from some of the earliest synthetic oils, which were glycol based and green. Things have come a long way since then, and the polyalfaolefins used in modern synthetics are in a different league. However, ‘green’ was associated with synthetics, so Duckhams jumped on the bandwagon, took a very ordinary mineral base stock, and chucked green dye into it – with incredible results in terms of sales."

[Rick]

Interesting.

On the other side of the argument, I've heard many people recommend avoiding fully synth in older engines though as they weren't designed to use it, it can cause problems with oil seals, and all the additives don't do things any favours either (I can't remember the specifics offhand, but no doubt a search online will bring the info up). I'll stick with decent quality mineral 20/50 in my oldies and change it regularly.

R
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[Job-Rated]

I think you all ought to take a look at the viscosity comparison charts of American & British oils. You will see that the U.S. oils are different. And better.
I only use Kendall & nothing else.

[Uncle Joe]

I'm going to add my comments to this topic.

There are quite a few wrong statements in the original quotation.

First off, Castrol. In 1899, a former employee of a company called The Vacuum Oil Company started what was to become Castrol Oil. His name was Charles Cheers Wakefield. The original company was named after him, Wakefield Oils. Between the wars, Wakefield Oil started to produce a Castor based oil, and became known as Castrol. In the 60's, Castrol were taken over by Burmah, and then around 2000 by BP. Mobil therefore have NEVER been involved with Castrol, although there is a connection with a similarly named company, Mobile (note the 'e'!).

Viscosity if there were two oils, one synthetic, one mineral with a 20/50 rating, then both these oils would have the same cold start characteristics, and the same hot performance. That is an engineering fact. The trouble is, synthetic oils have by nature a wider viscosity rating, eg 0W/50. A 0W oil will flow better at low temp, just because its thinner! But it will be the same at high temp, as a 50 oil! In fact, some people would consider it worse, because synthetics sometimes have a tendency to break down suddenly at elevated temperatures.

Reducing valve tappet adjustment intervals due to valve stem wear? Aah, come on guys.....Its not that that causes the tappets to close, its valve / seat wear! Of course, as a lot of modern engines have hydraulic tappets anyway, which dont need adjustment!

gilberry, maybe you want to quote me on this and post it on your Rover forum!

UJ

[gillberry]

Thanks UJ your reply is now quoted on my rover web site and I am awaiting replies . It certainly makes for interesting reading .

[Uncle Joe]

I'm so looking forward to seeing the replies....

UJ

[gillberry]

This is the response back from the chap on my other forum .


This is becoming tiresome. I’ll put you right once, then you can spout all the crap you like because I’ll lose interest.
And, as your wildly inaccurate and misguided post was challenging to the point of being insulting, I’ll pull no punches with my response

There are quite a few wrong statements in the original quotation. First off, Castrol. In 1899, a former employee of a company called The Vacuum Oil Company started what was to become Castrol Oil. His name was Charles Cheers Wakefield. The original company was named after him, Wakefield Oils. Between the wars, Wakefield Oil started to produce a Castor based oil, and became known as Castrol. In the 60's, Castrol were taken over by Burmah, and then around 2000 by BP. Mobil therefore have NEVER been involved with Castrol, although there is a connection with a similarly named company, Mobile (note the 'e'!).


This one is straightforward – you are totally wrong, I am right – I did not say that Mobile had been 'involved' with castrol, I said it was et up by ex-Mobil employees; other than corporate name changes (hardly worth mentioning at the time), that is true. Please read on.
Vacuum Oil was the first company to use vacuum distillation to produce more advanced ‘modern’ mineral lubes – hence its name. For interest, a key founder was a chap named J R Ewing – you may recognise that from a certain TV soap. It later became SOCONY Vaccuum, (SOCONY being Standard Oil Company Of New York, just as Texaco was Standard Oil company of Texas, etc). SOCONY Vacuum later became Mobile Oil, and that was renamed Mobil Oil.
Mobil evolved directly, in a straight line, from Vacuum Oil. So, please, get your facts straight before having the bad manners to try and tell me I’m wrong when, in fact, I am right.

Viscosity if there were two oils, one synthetic, one mineral with a 20/50 rating, then both these oils would have the same cold start characteristics, and the same hot performance. That is an engineering fact.

No, you confuse fact with ill-informed misunderstanding. You have no idea what you’re talking about – that much is clearly evident. Try very hard to understand this – I will explain it slowly enough for my dog to grasp the concept.
A mineral 15W/50 oil and a synthetic 15W/50 oil will have the same viscosity at just 2 specific temperatures. The “W” rating referes to the oil’s viscosity at zero centigrade - only. The other rating refers to its viscosity at 100 centigrade- only. That's what the rating means. Only at those temperatures will the mineral and synthetic have the same viscosity. The flatter viscosity index of the synthetic means – as I said in a post above – that is thickens less at low temperature, and thins less at high temperature.

You may be amazed to discover that cold starts can be necessary at below zero centigrade, which is when they get tricky, and oil can get to way over 100C in the sump.

Below zero centigrade, the synthetic hardly thickens up, while the mineral oil thickens considerably, and impurities tend to ‘wax’ and thicken the oil when you’re well below freezing. Try putting a cup of 15W synthetic and a cup of 15W mineral oil in your freezer for a few hours, and see which one will pour.
Similarly at high temperarture – again, as I said, the mineral oil will thin more above 100 centigrade, while the synthetic retains the flatter viscosity index and will not tend to go too thin – remember that sump temperatures can be well over 120C and when mineral oils exceed that, they get very thin and we risk film strength failure in bearings and on bores. Put a spoon of 50 weight mineral oil, and a spoon of 50 weight synthetic, in your frying pan and see the difference between them when you get them hot.

You challenge with “engineering fact”? I suggest if you wish to argue about tribology that you avoid doing so with a chartered mechanical engineer who worked several years in the oil industry in industrial lubrication.

The trouble is, synthetic oils have by nature a wider viscosity rating, eg 0W/50. A 0W oil will flow better at low temp, just because its thinner! But it will be the same at high temp, as a 50 oil! In fact, some people would consider it worse, because synthetics sometimes have a tendency to break down suddenly at elevated temperatures.

Utter rubbish – this is what we call a little knowledge is a dangerous thing, and I do not know where you get this nonsense from.
A 10W/50 synthetic will be thicker at zero centigrade than a 0W/30 mineral oil, but most likely be thinner at, say, -15C, because the viscosity index is flatter – meaning the rate of change of viscosity with temperature is more favourable.

As for breaking down suddenly at high temperature, this is plain silly. Your typical mineral engine oil is a hydrocarbon molecule with a few bits added on, but essentially about 30 carbons all jumbled up in various shapes – all quite erratic and not uniform at all. Some might, by dint of luck, be straight C30 chains, others will look like a dog’s dinner, if you could see them. The polyalphaolefin synthetics, like Mobil 1, are polymerised from C2 gas to make perfect straight carbon chains. They are isomers of the mineral oil, and therefore chemically identical, but because they are all the ‘best’ version of the molecule, they are more stable both to temperature and to mechanical stress. It is because they are straight carbon chains that they tend to break up less under extreme pressure – in gear teeth for example – and they are more stable to thermal breakdown. Synthetics are quite simply more resistant to elevated temperatures.
If you want an example, Lotus struggled badly to get the sump temperatures down on the Lotus Carlton, and it was frying mineral oils. The only way they could get the early cars to run right was to use full synthetic oil of a particular brand!

Reducing valve tappet adjustment intervals due to valve stem wear? Aah, come on guys.....Its not that that causes the tappets to close, its valve / seat wear! Of course, as a lot of modern engines have hydraulic tappets anyway, which dont need adjustment!

You are correct that the when valve clearances close it is due to seat wear. However, some engines, on inlet and/or exhaust, suffer from the valve clearances opening due to stem/lobe/rocker wear. In these cases, the lower friction and wear you get with the synthetic does reduce the need to adjust. Because the synthetic oil is made up of the straighter, more uniform molecules, there is actually less friction between working metal faces, which means less wear (and less temperatures build up).
And that, my ill-informed friend, is fact.


Some people on whatever other forum you posted may consider themselves well informed on the subject from reading their favorite monthly car magazine. - I make that claim from engineering qualifications, years in the industry, training in tribology, field trials with different lubricants in just about every industry, including automotive, and seeing the results from hundreds of engine test beds and as many industrial tests.
Feel free to tell me I'm wrong if your information comes from a better source..

[Uncle Joe]

The History of Castrol oil can be found on the Wakefield Trusts website.

As far as I can ascertain, the Mobiloil trademark was first used in 1920, 21 years after Wakefield started.

As far as viscosity goes, well, its correct what your informant says. Its either measured at 100C or for W grades, 0C. From first hand experience, I agree that synthetics flow freer under 0C, but only to a certain temperature....Many years ago, I actually drove a Ford Escort (with all synthetic oils) a few hundred yards in neutral with the clutch depressed..... So solid was the oil! Not for one minute saying the same car with mineral oils would have been better though


As far as synthetics breaking down are concerned, I've seen this first hand in practice about 10 years ago. The problem was solved by using a high quality non-synthetic oil....

This though, is my final word on the subject, on this forum at least.....

UJ

[giggles]

Don't you just love people like that!! Some people and I've found this from personnal experience, can be very brave when they sit behind the keyboard.

[Uncle Joe]

Giggles, why are you signing off Mrs Sniper?

UJ

[UKdave2002]

For what it is worth (and what I know about oil is that the best place to get it is Cosco ) A pal that I was at school with went to work for Shell innitially at Ellsmere Port, then on to R&D stuff, anyway he always maintained that the frequency that oil was changed was more important than the "quality" of the stuff, and that the cheapest stuff you get today is far better than most of the better stuff around 25 years ago.
The better modern stuff is needed because car maker's want to extend services to 20,000 miles +(which is what my modern is).

Every classic I have ever owned has leaked or consumed oil at a rate faster than it "wears" it out, which is why I buy the 20L for £18.50 Texaco stuff at Cosco!

This thread has reminded me that I need to change the oil in the Stag, allthough most of it is actualy quite new..........

Dave

[UKdave2002]

[giggles]

[Scotty]

It is disappointing UJ that the other responder on this subject has taken such an adversarial tone in his response, and all that's really been achieved is a lot of people wondering why he needed to present it that way. For me he lost the quality of his information by his obvious anger, so in the end up although he perhaps rebutted your observations competently, they were overshadowed by his manner of presenting them.

Granted it must be very frustrating being convinced they are right only to have somebody else suggest alternatives, however if somebody participates in a BB then they've got to accept they'll get the occasional "I don't necessarily agree" response to their posts, not everybody accepts what is written is the gospal regardless of how much experience or number of letters after your name. How many times time have we discovered that the brain surgeon on a forum turned out to be a shelf-packer in a supermarket (no offence intended to shelf-packers!).

All in all a disappointing outcome for you (and us) I would imagine - but we continue to live and learn.