I bought a Mitchell shop manual on Ebay. It has a maintanence section that says the engine oil change interval is 10,000 miles!!!! Can this be right??

 

with the dealership doing the change that is what they say i do mine on a 99 s80 every 6k - 7.5k at jiffy lube but keep an eye on oil levels

 

I would do the oil changes in these intervals.
Non-turbo cars 5K
Turbo cars 3K

Have seen tons of cars run the 7,500 services and get sludged up.

 

Ok. What about the oil filter, when I changed it the ohter day I took a Volvo brand off and put a Fram on, is there something special about the Volvo that makes it better?

 

Yes the Volvo filter has a check valve that holds the oil pressure when the car is off.
Mann is also a good filter.

 

You will get sludges all around.

 

I heard that Mann makes OEM oil filters for Volvo.
They just make oil filters with Mann title on them in the aftermarket. Of course, you can't find these in advanceautoparts

 

If you want to compare the fram filter and the volvo filter, you can pry open(whatever way you want to open) the filter, make the inner papers stretch, lay them down and measure the distance and find the surface area.
More the surface area, more particles it can trap.
I heard that if papers are way too tightly packed, they might block the flow, but I never had problems using OEM oil filters.
Usually it's the case that the OEM filters have larger surface areas than aftermarket.
Mann filters are not really aftermarket since it's the same as volvo ones. It's just that you can find oil filters with volvo mark on them at only dealers.