Since I am off factory CPO warranty I now change my own oil and wanted to use something besides the Castrol stuff. Nothing against it but I like and use Mobil 1 when possible.
I used Mobil 1 ESP X2 0W-20 as it meets the current oil spec of STLR 51.5122. Surprisingly I found it cheapest at Autozone and with free shipping I ordered 7 quarts at $9.99/Quart Item #125386. This is the regular price and currently cheaper than EBay or Amazon.

Now why I am posting is a bit strange because this is the oddest looking engine oil I have ever seen! It's a light green in color and is thinner than water at room temperature!



It just seemed way too thin to me but everything seems to working as designed and I believe the engine is quieter than before? Maybe my imagination as all these DI engines have a hell of a clatter to them anyway.
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Hi Club,

I use Motul Specfic which has a traditional amber color but, I agree that it does appear very thin in comparrison to older spec oils. If it does the job.....

wombat

Thank you for that post! That oil is scary looking stuff. I was going to look for other than Castrol too but I'm thinking I'll stick with the stuff from Castrol specifically designed for JLR just to keep consistency in my crankcase. Probably some dye in that Mobil One to make it unique. You'll sure know what's leaking when you see it on the garage floor. I had great luck with Mobile One in my old XJ8 and it actually gave me a couple more MPG when I switched. Let us know how this stuff works out.

It is good oil used it on my F type came out the containers that colour , just a dye , but all good

Take a peek at it under an ultraviolet light, may be a florescent dye so leaks can be better spotted.

Yes I think your right.
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That Mobil 1 oil meets the Jaguar specification STLR 51.5122, which has a viscosity of 0W-20. That's why it's so thin when it's cold. When the engine warms up and the oil reaches normal operating temperature it thickens and the viscosity becomes 20W.

The dealer-supplied Castrol Unobtainium had a unique dye to identify it as the correct oil for warranty purposes.

I think that's a bit backwards?
Increasing temperature decreases the viscosity of all oil. It does not increase it.
Oil Viscosity
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Nope. Confirming what I wrote ...
"Breaking down the 0W-20 code, “0” is the oil's viscosity at startup when the engine is cold, “W” stands for its winter certification, and “20” is the viscosity at higher temperatures. Lower numbers designate thinner, lower-friction oil.'

Source: Open this link and scroll down to ""What Higher-Cost Engine Oil Gets You":
https://www.cars.com/articles/expens...1420663058198/

See also: CASTROL "WHAT IS OW-20 MOTOR OIL?"

Well your still wrong? Oil gets thinner with higher temperatures and that is just a fact?
Why do you think differently?
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The oil is 0W when it is cold and when it is in its operating temperature it is 20W. If the oil goes beyond operating temperature it could break down but a synthetic oil has a very high tolerance for heat and it will break down over time but much of that is due to the impurities that the oil picks up over time and being used. That is why it is so important to change the filter and use a high quality filter. Today's oils are so good that it is usually the filter will fail before the oil fails.

Read the above CASTROL link.
Why do you think that CASTROL is wrong?

P.S. Here's an unedited copy of the relevant portion of that CASTROL link. The bold emphasis is mine:

"Motor oil viscosity is commonly measured at lower and higher temperatures. The properties of the oil at lower temperatures define the first part of the motor oil grade. In the example of a 0W-20, the “0W” part of the grade is related to the measurement of viscosity at low temperatures as defined by SAE J300 (and the “W” stands for Winter – relating it to low temperature performance). The better the oil performs at lower temperatures, the lower the number before the W. The numbers are ranges defined by SAE J300, so zero doesn’t mean zero performance; it means the oil performs better at lower temperatures and flows easier than oils that fall in 5W, 10W, 20W, etc. ranges.

The “20” portion of the 0W-20 grade relates to how the oil flows through the engine at higher temperatures – like when your engine gets up to normal operating temperatures. As a reference, think of it as how your oil flows when your engine has warmed up and you are driving on a highway. Again, the lower the number, the thinner the oil is and easier it flows around your engine. An oil that has a 20 after the W flows easier and faster than an oil with a grade that ends in 30, 40, 50, etc."

From Amsoil:
"Viscosity modifiers help reduce the rate of viscosity change when temperatures rise or fall. This helps the lubricant provide better performance over a broader temperature range.

Polymers and copolymers of olefins tend to expand as the temperature rises, counteracting the oil’s tendency to thin.
AMSOIL: About Motor Oil Additives

simplified description of multi-viscosity oil might be helpful...
Understanding Multi-Viscosity Motor Oils (ezinearticles.com)

one excerpt from that article:
..."Petroleum oil will thin out far more at high temperatures than synthetic oil will."

Ok,

First off, I'm not an expert on oils or the viscosity of oils vs temperature, however, there are many fluids that DO increase viscosity when temperature rises (Cheese sauce springs to mind).

To my mind the 0W20 gives an indication of its viscosity at 0C, and its ability to cope with higher temps...we used to call it multi-grade. I think that it shows the scope of the oil and the fantastic design of modern engines....they basically run on slippery water.

wombat

the w scale and the hot scale are different. In other words, just like all motor oil, the oil is thinner when warm.