As my wife's 850 has now passed 100k, the service manual says to "see the Dealer". I trust them, but want to go in with a clue. Do I assume that I just add 100k to the beginning of the maintenance schedule? There seem to be a lot of check fluids that I can do, not to mention oil changes! Thanks for any advice.
Mike - 94 850

Don't you have a maintenance book that should have come with the car as it shows what's required? 100K does NOT mean that the clock starts at zero again. A 100K service is basically the same as a 10K service (assuming that your 90K was done?) and if it's a '95 on up 850, it gets a fuel filter at 100K too (pre-'95s like yours were every 60K).
The 120K is 60K miles past your last 60K service so that's what it should get then. If '94 on up, the T-belt is replaced at 140K miles or if a '93 (and early '94s), every 50K so at 100K, then it's replaced or should be. Note: SOME early '94s have 50K T-belt intervals determined by the 6 digit engine # SO if in doubt, ask a dealer parts guy as he's got access to that T-belt info.

Any US Volvo dealer has OEM maintenance sheets supplied by Volvo and upon request, any service writer can and will show you these sheets for your car (any Volvo) and explain the details.

Eeep! I didn't know that some '94s had the narrow timing belt!

The maintainance schedules should be available on the Volvo NA website under "virtual glovebox". You need to register. I don't think they are 100% accurate (NOTHING from Volvo NA ever is!), so you need to use your head. 100K is typically cabin air filter and gas filter, in addition to oil and filter change.

I'm considering also doing the tensioner and water pump with my 140K timing belt service.

-Punxsutawney Phil