Hello.
Can I ask where you had it done?
I am seriously considering a GS300 as they seem to be very good value at 9 or 10 years old, and I believe the oil burning/carbon build up issue is more of a USA problem due to their low quality fuel. Other than that they don't seem to have any major issues.
I'm a firm believer in auto fluid changes - everything deteriorates. I've had several auto cars, all have benefited from a fluid change. Changes got quicker and smoother. I think fluid changes should be part of a standard service about every 40 or 50k.
Cheers