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I've had my 2008 XF 2.7L diesel since new in August 2008. It has performed flawlessly. I only use it for long distance cruising and as I live in Australia that means trips as long as 5000 and 8000km plus. Even a 1300km day trip is not uncommon.
Recently I have been reading articles and some YouTube clips where there has been discussion about changing the oil spec from the 5W-30 to 5W-40 on the basis that the more viscous oil improves lubrication, bearing life and results in a quieter running engine especially for older cars and higher mileage cars. Of particular interest to me as well is that the more viscous 5W-40 is also better suited to operating in higher temperatures and that is certainly the case in Australia. On a recent road trip I experienced 3 days of 40 plus degrees celsius temperatures meaning road temperature is up around 50-60 degrees C.
Whilst that seems to all make sense to me and JLR actually specify 5W-40 for Land Rover diesels in South Africa (hot climate), I haven't been able to track down a proper technical opinion to help make an informed assessment. Of course the usual advice says if that's what the manufacturer has specified then stick with it as well as the adage if it ain't broke don't touch it.
However with all that in mind I'm trying to think for the future and desiring to keep my amazing car forever!!!
So current mileage is 129,000KM, age 16.5 years, operating temperatures up to +50C, principal driving profile - 10% city driving - 90% long distance country driving in the 100km/hr to 130km/hr range.
Any thoughts advice, reference to technical reports etc would be appreciated.
5W-30 versus 5W-40 Engine Oil
