Even the waterproof ones, you should clean out the heads and re-oil somewhat regularly, and you can use mineral oil when you run out of the tiny bottle of oil these machines usually ship with. It drains the batteries a lot less when it’s well lubricated too. I’ve had one for also about 10 years, uses double A’s, but I change them maybe once every two years.
Even the waterproof ones, you should clean out the heads and re-oil somewhat regularly, and you can use mineral oil when you run out of the tiny bottle of oil these machines usually ship with. It drains the batteries a lot less when it’s well lubricated too. I’ve had one for also about 10 years, uses double A’s, but I change them maybe once every two years.