100.000 mi. Maintenance

[KJUN MAN]

My 2001 Pontiac Firebird is coming up on 100,000 miles and will need an oil change soon. I do not know what type oil was used but it appears it was not any High Mileage or Mobil 1 based on the oil filter. Should I just put regular oil in it and what grade is recommended? It does not have an oil leak and I want to keep it that way.
Also, I feel it needs to change transmission fluid. Again, there is no leak. Should I have the transmission flushed or will that possibly cause a leak that was not there before?
I want to keep this bird as free of problems as possible, so would appreciate any assistance in this regard.
If this subject has been broached previously, then please accept my apology. I am new to this forum and got in to get help with maintaining this fine car.

[2.8 Bird]

Re: 100.000 mi. Maintenance

Do you have a manual that came with the car? Everything you want to know about basic car maintenance base on mileage is on that car manual.

If you want to keep your Bird leak free then stay away from synthetics. I was told by a professional mechanic before that it can cause oil leaks. But I would rather use full synthetic and have some minor oil leak like I do now.

If not then be sure to keep changing your oil every 3k.