When scraping old gasket material from an aluminum cylinder head or crankcase joint, why should you avoid using a hardened steel scraper?

1. Hardened steel can easily gouge and scratch the soft aluminum mating surface, creating paths for oil and combustion leaks.
2. Steel scrapers react chemically with aluminum, causing rapid electrolytic corrosion.
3. The steel scraper will magnetize the cylinder head, attracting metallic debris.
4. Aluminum residue will permanently coat the steel scraper, rendering the tool unusable.