As AlexB says
Find a good synthetic 5W40 ACEA B3 B4 oil (pm oilman for a specific recommendation)
Oh' and half your oil change interval, (9000 not 18000 as early 1.9dCi's do unfortunately suffer Turbo problems

)
Slightly off topic.
My new Laguna 2006 2.0dCi Sport Tourer was serviced by a Renault dealer in Oxford at the begining of October 07 at 10200 miles. Oil used ELF SOLARIS RNX 5W30 C3
Whilst this is a very good oil it's not correct for my engine.
It was then serviced again by the Renault to Go service depot on 24th October at 10313 miles. Oil used ELF Evolution SXR 5W40 ACEA B4 the correct grade for this engine.
So it did 113 miles on oil that was probably very expensive, and not right for my engine
What concerns me is that some Renault dealers once again seem to be using a one-for-all oil policy and the wrong oil at that.
