I have a smaller version of the Vetus bow thruster and the manual (which is for a number of types) says that the thing contains lubricant for “longer term”. There are no instructions for changing the oil (unlike the anodes for example)
Tnx Eric, there does not appear to be a manual on line for mine.
But just stumbled on a similar one which is on line, will be checking the brushes in the near future.
Did mine recently when boat ashore., 18 year old Venus 50kgf. Drain plug was part of anode base mounting on gearbox. Removed anode and unscrewed plug with spanner. Positioned half litre container. Took lid & filter cover off thruster gear box header tank under forward bunk then removed plug. About 0.3 litre very black gear oil came slowly out on a warm day. Flushed gearbox through with about 0.25 litre gearbox oil.The manual recommended putting replacement oil into header tank and waiting for it to start coming out through drain and then replace plug. Did this and then filled header tank with about 0.25 l gear box oil, per indicated capacity which is near full on header tank. Cleaned prop and reassembled.
Relaunched and thruster works satisfactorily, also being quieter. Watching oil level carefully per manual recommendation and am expecting level to drop slowly as gearbox slowly fills in use. But level not falling as quickly as expected. Hope that helps. DB