[KozmoNau7]

Short answer: buy less stuff.

Longer answer: reduce your buying habits. Keep your laptop/phone around for longer before replacing it. Buy second hand or refurbished devices.

Do you need to buy water, or could you drink (filtered) tap water? Do you need to buy milk, or can you replace it with an alternative? Soy and oat "milks" are different, but serviceable replacements. Avoid almond and other nut "milks".

Sometimes you can't really avoid the packaging, but you can make sure the product in that packaging has a smaller environmental impact.

As for motor oil, most cars only one oil change per year, so that bottle of oil isn't the worst item in your example. But you should probably drive less.

[Spooky23]

In other words, ignore the problem and do something else that gives a warm fuzzy feeling. Replacing milk with a more expensive, processed alternative has nothing to do with a plastic bottle.

The global solution to reducing plastic packaging is to reduce the use of plastic packaging, mostly by using cardboard and glass instead. That's driven by manufacturing, not consumer action.

[KozmoNau7]

You were specifically asking from a personal perspective, so I gave answers from the same perspective. That does not mean that I discount the impact from corporations, in any way whatsoever.

Lifestock farming is one of the biggest contributors to climate change. By choosing alternatives, this contribution can be lessened. I very specifically said not to buy nut milks, because they're also rather bad for the environment, especially in terms of water usage. Soy and oat milks have lower impacts than dairy and nut milks.

Just because your individual action doesn't make much of a difference in and of itself, that does not mean we should just give up. Obviously it shouldn't be a case of ignoring the big polluters just because you did a small thing, but by changing our habits, we can use consumer demand to change the production and packaging practices of corporations.

Individual action does make a difference. Everything counts.