[Charles Hunt]

1. My Jaguar XJ has the smaller, Ford 3 litre V6 engine which requires a 'Ford' specification engine oil.

Really? Does a particle of aluminium alloy or nikasil coated something or other really know whether it's in a Ford engine rather than anything else? Or do Ford use some some particular material or coating that will be adversely affected if the magic 'Ford' spec is not used?

2. Aero Engines

Again we are told only use 'Aero' engine oils for aero engines. Is there really any difference in the materials in a 912 (Water cooled) than in an auto engine.

I can imagine that the heat transfer requirements for an air/oil cooled engine may be different to those for a water cooled, but is their any magic ingredient added to oils for air cooled rather than water cooled.

Is there really any difference in the requirements of a lycosaurus or Jabiru than say a 70s era oil/water cooled motorbike engine?

[mikehallam]

Yes !
e.g. The 912 gears share engine oil & Rotax prescribe motor cycle oils. Also the oil becomes more contaminated with leaded fuels thus halving oil change hours. They recommend non leaded fuels.
Now you might be tempted to advise on suitable viscosity and oil change intervals too ?
Ford presumably know more exactly what their oil brand contains, or perhaps it is what they test with.
l agree Rotax do/did give a list of brands etc. which gets updated.
Problem nowadays is very few folk have any technical knowledge, let alone in depth, hence Ford' s recommendation.

[Miscellaneous]

Or do Ford use some some particular material or coating that will be adversely affected if the magic 'Ford' spec is not used?

Unlikely they will have a special coating. It's not so much the engine as the oil. A Ford spec oil will be either (or both) an oil made to the spec Ford determine, or to an international spec. with Ford approval. Oils not to Ford spec are therefore unknown.

https://en.wikipedia.org/wiki/Motor_oil ... itute_(API)

2. Aero Engines

Again we are told only use 'Aero' engine oils for aero engines. Is there really any difference in the materials in a 912 (Water cooled) than in an auto engine.

Again its not so much the materials, although they can of course differ, as it is the oil and additives. In addition to the Rotax gearbox the operation of aero and auto engines differ. The fuel used, power settings…

To give an example; in days gone by a change from an old traditional mineral oil to a modern day oil with detergent additives could result in the years of sludge deposited around the engine being 'lifted' by the detergents and causing problems. Same engine…different engine oils.

[Trent772]

Your Ford handbook will have reference to an oil spec as described in the Wikipedia link. Any oil that meets that standard will suffice. Modern cars seem to run on a 0-20W oil which is very thin, but thickness of oil bears no relationship to its lubricity or performance.

I ran 2 Toyota Hiluxes over 10 years, I bought my oil at Walmart in Florida and fetched it back ( no, it's synthetic and non hazmat) and gave it to the dealer at service time. Saved me £70 every service as I was paying $30 a big bottle instead of their inflated prices.

Aviation oils are different.

Lycosaurus etc have very high temperatures, need stable oils, generally with dispersant properties (pedant warning, it isn't detergent ) It also has to cope with the lead in our fuel and the high levels of contaminants due to sloppy old designs - blow by etc. Hence why calendar oil changes are so important, not just waiting for your 50 hours. 6 months max between oil changes

Rotax need a wider performance oil that can deal with the gearbox as well and is designed for unleaded. Run leaded and the contaminants build up quickly hence the more regular changes.