Dad has moved to assisted living and left me to deal with his baby (79 280ZX black w/gold trim, 54,000, yes 54,000 miles) never been housed outside, always had a cover inside) I am trying to sell it and have found a good, local, potential buyer ($27,000). He is coming by this weekend to take it for a test drive. I am going to replace the battery....it has been sitting for years without regular driving, battery is weak. I also need to add gas to it. I don't know anything about it other than it should take leaded gas! What do I add to the unleaded gas to make it run better. I was told there was an additive that can be added. Please help! I know nothing about cars.

Chickenlady

For fuel, fill it with a name brand gas station fuel.  Regular is what the car runs on, no advantage in using another higher octane grade other than if non-ethanol fuel is available in your area,  Add a bottle of gas line antifreeze / water absorber to eliminate any moisture - water in the fuel tank from sitting for extended periods.

The car really needs to be driven to restore its driveability and performance.   The potential buyer should understand that.

Nice looking car,  my favorite - original & unrestored.   Best of luck with sale!

According to the owner's manual for 79, it does not need leaded gas. 

Thanks everyone! Just saved myself a lot of trouble!

i suggest you put a charger on the battery and just let the owner know it's due to be replaced. Chances are the gent buying it won't put a standard lead/acid battery in it. 

Thank you Pilgrim! I wouldn't have even thought there were different types of car batteries.

Chickenlady

Drive it for an hour and watch the gsuges. You'll feel better selling the car if you know a little.

Should sale quick! It's a nice car.

Thanks siteunseen, I wish I could drive it for an hour but it's been unregistered for a while and the last thing I need is to get stopped. I haven't driven it for 30 years, if backing out of the garage doesn't count.