Diesel 2.5 vm engine running 5w/40 oil.

[si-h]

The owner of my taxi has informed me that from now on, the 2008 cab with 250k on the clock, will use fully synthetic 5w/40 oil. Over the past two nights, 7 litres of Asda's finest oil has smoked out of the exhaust....... An oil consumption never seen on this cab ! 1L per week normally.
Even thought the manufacturer states this is the correct oil, am I correct in arguing this oil recommendation only applies to a new engine, or an engine that has always used this oil.
Am I correct in saying it is way too thin, and way too late to start using this oil ?
Any technical wise words of wisdom to support my stance ?

[radical78]

dont change type of oil at that milage go back to what youve been using if its done 250k it was ok

[paintman]

Too thin. Unless you want to blow it up or run effectively a constant loss system.
The 2.4 & 2.5 VM were used in the RRC & the recommendation is for 15w/40.
Have a read through the manual:
http://www.roversclub.org/docs/Range%20Rover%202-4...

That said, its his to do with what he pleases, although I suspect an earner off the road requiring a new engine won't do that!

Edited by paintman on Sunday 16th November 20:49

[Pumaracing]

I would be extremely doubtful whether a change to any grade of oil would on its own increase consumption 20 fold. Maybe there is a leak as well. However it's a simple test to revert to the previous grade of oil and see if consumption also reverts to its former level. Going to a fully synthetic at high mileage can remove carbon and tar deposits that ends up doing more harm than good as the deposits may have been taking up clearance in things like valve guides that actually helped keep oil consumption down. However undoubtedly 5/40 is not the recommended grade and is too thin. 15/40 or even 15/50 at that mileage would be better.