“I haven’t changed my engine oil for/in a year. My car only went 3000 km last year.”

> Are “for/in” both correct here? Yes. > Do “my car went 3000 km last year” and “I drove my car for 3000 km last year” sound natural? You mean, "Does", not "Do". "My car went 3,000 km" sounds odd. We'd normally say, "I drove for only 3,000 km" or something like that - unless you are specifically trying to say that others drove it. Please use a comma in 3,000. > How would native speakers put it? I've not changed my oil for over a year, because I only drove 3,000 k. ("k" is slang, but quite common. I'm actually from England, so I wouldn't normally use km, I'd use miles, but eh.)

Both "for" or "in" are correct, though I think "for" will be more common. I wouldn't say there's any difference between the two of them otherwise. I would not expect to hear "My car went 3000km last year" if only because a car doesn't "go" anywhere on its own (unless you've got the latest technology and want to draw attention to it). Maybe that doesn't make total sense, mainly it's because people don't use "go/went" like that in English. "I drove my car 3000km last year" is right. You don't need the "for" preposition you included in your example. Another ways a native speaker might say it would be "I only put 3000km on my car last year."

1) in, though for sounds natural too 2) my car only did 3,000 kilometres last year. Australia

In. For sounds odd in this context and seem to indicator a duration for the event rather than an amount of time since the event. For example: I was at the beach for 10 hours. I threw up for half an hour. I lived in Italy for a year. I have never bathed for two hours. I prefer to only bathe for one hour.. -////-// Saying you haven’t changed your oil for a year… Almost implies you have not stood under the car working on it for the entirety of a year. For example: I have been rebuilding this classic car for a year. I haven’t been studying English for a year