1. Turn OFF electrical/circuit breaker (usually, this is directly on the generator; but it may be next to the transfer switch).
2. Turn generator run switch to the OFF position.
3. Wait at least 5 minutes to cool down.
4. Check the oil with the dipstick, and fill SLOWLY, WITH SMALL AMOUNTS AT A TIME, as needed (usually, National Standby leaves extra oil near the unit). Check the dipstick frequently as you fill, to avoid overfilling.
5. Restart generator in the AUTO position.
6. After engine has run for about 1 minute, turn the same electrical/circuit breaker back to the ON position.