The throttle spring actually does not impose a lot of load on the throttle servo. I once measured it and the number was around 5 oz. It is not a bid deal to a standard servo.

For break-in, Penzzoil air-cooled oil is also good and is available from amazon.com, [link=http://www.aircraftspruce.com/catalog/eppages/pennzoil.php]aircraft spruce[/link]. 8 oz @ $3.35. 32:1 ratio.