After not using any oil before, dipstick surprisingly shows no oil in engine

Oil consumption generally does not jump up like that unless it leaked out, was not completely filled in the first place, or the dip stick was not inserted all the way. I'd monitor oil level closely in case it was not a fluke.

You had the oil changed, implying that a service did the work for you. Were the people doing the work clueful? Or did you go to "Spiffy Lube" quick change place, where the people doing the work couldn't find their tush with both hands and a road map?

Yeah, they may have filled the oil with three quarts (instead of the right amount (five or so, depending on the engine) and measured the level - with the filter empty, because they hadn't started the engine yet. That will account for almost one quart right there.

Other than under-filling, it has to go somewhere - be vigilant for a while till you rule out trouble and call it a fluke. If it's being burned rapidly, you'll see it. If it's leaking rapidly, you'll see it.

I've been to these "Spiffy Lube" places a few times - and each time I've been less than impressed. Good thing I was watching, because they didn't even know to buy a vowel from Vanna. While I had a broken foot and wasn't up to doing it myself, I had them service my Corvair - It was the only Automatic transmission car in the family at the time, and with no usable left foot available...

And I had to stand there on crutches and explain how to do it, because nobody in the entire place had ever seen a Corvair before - they didn't have anyone there over 25, Manager on down... This is Never a good sign.

("No, slip a plastic bag over the oil filter, or you're going to have a big mess to clean up..." "No, it won't 'just drain away', can you see that skirt seal between the engine and the body? It keeps the cold air on the top and the hot air on the bottom.")

("It's not in the computer? Why am I not... Okay, it takes an AC PF-4 and 4-1/2 quarts. You don't have a filter? I have a spare filter in the trunk. Whaddya mean 'Where's the trunk'? - try the other end..." )

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LOL! My Uncle had a '69, brand new, and I had a '66 with a 3 speed, and Fred Flinstone brakes (the floor behind the driver consisted of the carpet and the mat..."Don't put your feet on the floor!")

Nice little car. Too bad Nader made his fame killing the best idea Chevy had for a long time!