Volvo: general volvo, volvo 850 glt, quality brand name

Question
ok ray, I bought a 1997 volvo 850 GLT, I just want to know a few things. What's the difference between a GLT and a regular 850? What does the 850, 940, S70, S90 etc. what does all that stand for? What aftermarket parts can I put on my volvo? And lastly, the sticker that says that I need to change my oil says I should have changed it at 95000, (approximately), and I now its at 98000, (approximately), my check engine light has come on, do you think it's because of the oil? wut kind of oil should I use if I need to change it.

Answer
Vic,
GLT is a trim package and interior style. Not a plain or base model, a nicer not so plain interior.
You are due for that oil change, 10W30 in cool to warm climate, and 10W40 in warm to hot, use a good quality brand name oil. If the check engine light is on then there is a trouble code stored in one of the on board control units. The code needs to be read via a scan tool and repair the fault, then the code can be canceled. 850 S70 front wheel drive 5 cyl. S 70 was the replacement of the 850 same platform just newer cleaner lines and interior. 940 S90 rear wheel drive 940 is 4 cyl turbo or non turbo S90 very simiular body with a 6 cyl.