It's 6 one way, 1/2 dozen the other...
I've had cars sit for longer than that with full tanks, and never drained the fuel to start them up. The '85 has sit a couple of times for that long, with no problems when it was time to fire it back up, although a fuel filter change was warranted. My 'Burban sat for 4 years without starting at all...fired right up when I got ready to drive it again.
Really depends on the quality of the fuel to start with, the condition of the tank, and the environment...where does the car sit? Outside? In? Hot weather? Freezing cold? Humid? Dry? ALL of the above? Was there any fuel stabilizer put in it before it was stored?
Take the cap off and smell the fuel. If it don't smell like gasoline, it might be best to drain/refill. If it still smells like gasoline, I'd say fire that puppy up, and go for a ride!
If you're that concerned, drain it, and use that fuel for your lawn mower/tractor, so it won't be a total waste.
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Joel Adams
C3VR Lifetime Member #56
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"Money can't buy happiness -- but somehow it's more comforting to cry in a CORVETTE than in a Kia"