When in doubt, change the brake fluid, antifreeze, PS fluid, tranny, and engine oil. Use synthetic! It lasts much longer and stays cleaner.
Your tranny is an automatic 5 speed and requires synthetic fluid, either very expensive Volvo brand or slightly cheaper Mobil 3309.
PS fluid should be bought at the dealership, using only 1 liter makes the expense relatively small.
Use Volvo brand spark plugs, if yours are starting to show age.
Change the air filter and cabin air filter (behind the passenger kick plate), and time to change the fuel filter.

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My name is Klaus and I am a V ♂ lv ♂ holic.