Some of the links on this forum allow SMF, at no cost to you, to earn a small commission when you click through and make a purchase. Let me know if you have any questions about this.
The only thing that needs "seasoning" is the grill itself! Fire it up, get it hot, hit it with spray oil, let that cook on for five minutes and you're good to go...
I had to replace my Weber kettle last year. After the tears in my eyes dried, I went with the Silver 22.5 as it was the closest match to my 80's kettle that finally died.
To get a good season on the new kettle, I talked to the butcher at the meat counter at the local supermarket and he gave me about 10lbs of fat that had been trimmed for various cuts for the counter. I put all 10lbs on the grill with a full load of coals. Cooked the fat until it all turned to ash. Took about 6 hours and most of a large bag of Kingsford. The effect was a good flavor coating on the I side of the lid and on the cooking grate. Looked like it had already been used for years. Still lost a bit of flavor compared to the old one, but much better than a naked kettle.