Aftercare for head gasket replacement on 1998 GMC Suburban 1500

I will be having a head gasket replaced on my vehicle. The vehicle will have been sitting a while before the mechanic I've selected can get to it. So, I have two questions-what can I do to "refresh" the gas (the tank presently holds @39 gallons, since I had tanked up before I drove 15 miles and had the gasket blow)? Also, since water got into the block, what sort of aftercare ought I to do to keep the vehicle in good repair, and attempt to prevent future failures?

Thanks ahead of time!

Ian Shaw

they have gas additives u put in fuel to keep it from going bad. they use it in boats its called sta-bil put some in tank this will help. have mech insp cyl walls after heads are off to determine if cyl's are rusted or not. if they are good repl oil after a few hundred miles and then again after 500 miles then go to reg maint at 3k
Thank you. I have also been told to use Sea Foam for a few oil changes to get all the water out-is this accurate and advisable, in your opinion?
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