I would not trust any garage, Dealer, independent or the garage under the arches !
If I have to use a garage for a job I cannot do I always inspect their work afterwards.
I always service mine myself following the manufactures schedule adding anything I feel necessary such as halving the Renault
change intervals., When draining the
I leave it to drain for the length of time it takes me to service and inspect everything else, about 2 hours, unlike all garages that give it about 2 seconds of dripping before screwing the sump plug back in as another vehicle is waiting to be serviced.
minor, interim and full service only means what the garage wants it to mean ! It could mean anything.
My son took his porsche 944 to an independent to be serviced, I don't know what
they used but the engine was very noisy, I changed it for the correct quality
and it went quiet again.
Most drivers and even garages do not even know what
should be in the engine !