I have an XKR with the 5.0l SC engine and from what I have gathered on many posts is that following the initial release of that engine in m/y 2010 JRL found that the timing chain tensioner which is run from pressurized engine oil could take too long to come up to pressure and the chain slip off the track...essentially blowing up the engine. One of the remedies to this was to change from 5W-20 to 0W-20 so that the oil would be thinner on startup and pressure would build much quicker for the timing chain tensioner. So its less about fuel economy and more about fixing a somewhat flawed component in the engine design. I change my own oil and as has been noted that in the US its nearly impossible to find the specified castrol as dealers get it in drums, I have been using Amsoil which according to their published data meets Ford WSS-M2C945-A for the 5w-20 and Ford WSS-M2C947-A for the 0W-20. I've been using these for years without issue.

 

This makes sense and is really important if it works for this purpose. Has Jaguar weighed in on this or just word of mouth?

Either way I am going to try this out to tell you if it works. I use 5w-20 and my chain is starting to rattle on cold start. I will take a video of it before and after oil change. Thanks.

 

A lot of it is word of mouth, and occasionally service dept. techs who are willing to disclose the issue. It seems that JRL didnt really want to officially address the issue through any type of recall or specific TSB, though there are TSBs for 5.0's that have a ticking sound on startup, usually from a bad hydraulic chain tension actuator.The below thread goes into details on it

https://www.jaguarforums.com/forum/x...-techs-159928/

 

Apparently I’m already using 0w-20. So I guess there will be no video showing any difference. Sorry