Engine Oil - The Brand or the Spec?

[T-Cut]

The earlier post about Comma Oil got me thinking. Now I'm out of warranty (the 75 that is), I should think about what oil I'm going to use when I next get out and get under for an oil change. Everbody knows the 75/ZTs petrol engine range requires 10w-40 oil to ACEA A1, A2 or A3 specifications and the diesels need 0w-40, 5w-30 or 5w-40 to ACEA A3 and B3 specifications. By definition, any brand of oil complying with the appropriate spec is acceptable. If two oils meet the relevant spec, then by definition they are equivalent. So why is it we tend to favour a big name, Mobil or Miller for example and not Comma or Mr Bloggs and Co.?

Looking at the eBay offerings for semi-synthetic lubes, there are some pretty interesting deals on lesser known brands. Some are almost half the price I've been paying my local MGR Main Dealer (Ex. that is) for the oil. So should I continue paying top whack for my engine oil, when Joe B is offering exactly the same spec and a considerable saving?

TC

[tigerchubs]

Comma oils and many other brands including Halfords own brand come from the Fawley refinery, owned and operated by Exxon Mobil the same plant that produces Esso & Mobil fuels and lubricats including Mobil1. So you can be sure your not getting substandard or reclamed oil as some of the really obscure brands are.

what can be said about buying lubricants from main dealers, at least DickTurpin covered his face while robbing folks.

[MartinW]

If two oils meet the relevant spec, then by definition they are equivalent. So why is it we tend to favour a big name, Mobil or Miller for example and not Comma or Mr Bloggs and Co.?


Note that with ACEA ratings and with API (American Petroleum Institute) to some extent, it is not necessarily about better performance - rather it is about a category of oil rating. An oil submitted for test must meet or exceed minimum criteria to be considered for that category. That denotes that two oils of the same rating are not necessarily equal. I have done tests on diesel engines operating under identical conditions and found twice as much cam lobe wear on on the one oil compared to the other of the same rating.

The criteria are set based upon current engine technology - as you will have noted over the years engine design has changed somewhat and factors like EGR put more soot in the oil, for example. Thus each category is denoted by the typical engine design and issues relevant at the time the category became ratified. What isn't necessarily rated is the oil's potential service life. That will be somewhat dependent on the base stock and additive formulation so the price will again vary within a category.

It also costs oil companies a small fortune to get these approvals and to research the formulation for performance and compatability. Certainly marketing costs are high, but there's also litigation protection against warranty/health&safety claims etc that are factored in, too, so costs will vary. In addition, if you buy in bulk you won't pay Halfords prices - Mobil 1 can be bought from places like CostCo at half the price - I have had it from a motor factors at £20 per 4L.

Certainly, oil is either sold down to a price for the tight-fisted amongst us, or sold up to a price for the enthusiasts amongst us. It's your choice!

[MartinW]

One other small point, there are over 60 lubricant product companies in the UK, not all for automotive I hasten to add. These companies buy the base stocks from majors, and the additive packages from chemical companies like Lubrizol, Infineum, Oronite etc and blend and package on their own site. The product may originate from a major refinery, but there are many further processes before final delivery that can affect the quality.