I would be cautious based on the fact he mentions it needs fluids.
How do you know it was not run low on oil, or the oil was not changed for 20k miles?
Just don't expect a perfect car for $1000. I would plan to at LEAST another $1000 to get it back to where it needs to be, probably a lot more.
I'd offer $700 cash if it drives without any major noises in the engine, or
any transmission slippage. If there are any bad noises or the transmission slips walk away the car can very quickly put you $2k+ in the hole for the transmission alone.
Mileage from the engine is BS. Odo is broke, end of story. You are taking a gamble. Check the VIN
BEFORE you buy it to compare mileage at smog checks for authenticity.