I know this subject has been done to death… but being a bit of a boffin I decided to do some proper research on this topic (that’s just a fancy name for googling…). I can’t guarantee that the info below is the gospels, it is what I found on the Internet, but having cross-referenced several sources it seems very likely that the information provided is indeed correct. So here goes:
1. Modern engines burn lean mixtures in order to improve economy and reduce emissions, which results in typically higher working temperatures. Under these conditions oil tends to break-up and this is why higher-quality oils are needed, i.e. semi or full synthetic, which have better resistance to higher temperatures.
Or this is the official version anyway… the real story behind high-performance oils is the drive by motor manufacturers to increase service intervals. This is a major issue for fleet buyers – and manufacturers sell cars on the back of low running costs. The fact is that if the manufacturer’s official oil change service schedule are ignores (for Omega, it’s 10,000 miles for the 2.5/3.0 and 20,000 miles for the 2.6/3.2) and the oil is changed at the traditional 3,000-5,000 miles interval, it does not really mater much which oil type you use… any modern good quality oil, be it mineral (yes, even mineral), semi, or full synthetic will perform well during this relatively short period.
There is no doubt that full-synthetic oil provides better protection than semi or mineral oil, but the point is that this is marginal under normal use and when the oil is new. Where the full synthetic really shines is if you actually keep the oil in the engine for the full duration of the official service schedule interval – but this is something that we here don’t recommend anyway….
2. Not all ‘synthetic’ oils actually synthetic… apparently enhanced mineral oil can also legally be called synthetic.
The paragraph below is from Honest John (he wouldn’t tell a lie, would he?):
‘The most stable products on the market and those which are being chosen by manufacturers for extended service are fully synthetic PAO (PolyAlphaOlefin). This includes Castrol SLX, Esso Ultron and Mobil 1. These products are extremely stable in extremes of performance….’
Note: Castrol SLX is not the same as Castrol Magantec. In fact Mobil sued Castrol claiming that Castrol call their Magnatec oil ‘synthetic’ were it is actually enhanced mineral oil, but sadly Mobil lost the case and the result is that enhanced mineral oil can now be legally marketed as synthetic…
But is it possible to know which oil is which? Yes, if we look at the Mercedes-Benz spec. MB have several oil specs: MB 229.1, then MB 229.3 (and its diesel subset MB 229.31), and the latest is MB 229.5. Only real fully synthetic PAO oils can meet MB 229.3 or higher.
Going back to point number one, as long as you buy good quality oil and change it frequently is shouldn’t matter much is the oil is ‘real’ synthetic or not. But even if using mislabelled oils may not actually damage the engine, you do want to know what you are buying and where your money goes….
3. As for Esso Ultron, it is made by ExxonMobil. My parts manager swears that it is the same oil as Mobil 1, coming off the same tanker, and that buying Esso Ultron is really just buying Mobil-1 for less. Whether this is actually the case it is difficult to say, but what seems to be clear is that they are both made from the same base oil (though potentially with different additives), so Esso Ultron is a very high quality full-synthetic oil and does cost less than Mobil-1.
What is even more interesting is that several sources on the Internet claim that Halfords’ own-brand full-synthetic oil is actually Esso Ultron – if this is true, then buying it from Halfords with Trade Card will be on par with buying Vauxhall own-branded oil on Vauxhall Trade Club.
4. This is all for boffins… I don’t know which oil Vauxhall use as own-brand, but again, it does not really matter - if you change oil frequently as you should then either Vauxhall semi or full-synth will be very good choices, especially on Vx Trade Club or when they are available on 4-for-3 special offers!
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Topic: The definitive oil thread… Part 1 – Synthetic Oils (Read 4062 times)