What exactly do they do in a service.

[rg500gamma]

Synth and semi synth has many advantages over mineral, no one is disputing that. The question is are those advantages of any benefit in the GS5 and is the increased cost justifiable.

My opinion is a resounding NO!!

BUT........If the machine in question wasn't a 35 year old, air cooled, carb fed dinosaur with massive internal clearances and instead was a state of the art high performance high reving, fuel injected, multi-valved/cammed/cylinder liquid cooled piece of race bred exotica I would have a different opinion

As mentioned I use a Motul semi-synth and guess what.....I have had no issues either. I also mentioned it costs about a third of the full synth.

Why should I be paying three times as much to get the same thing?

yes   semi-synthetic  great oil  as well