I drive a 1999 Altima GXE with 84K miles. I'm thinking about doing my own oil change now. Can anyone recommend me the best "synth" oil? How much oil do I need to my Altima?

 

You don't want to put synthetic oil in a car with 84k miles that hasn't used synthetic for the life of the vehicle.......I would recommend a maxlife oil.

 

If you want to switch to a synthetic oil now, I would go with one of the better known brands, Mobil1, Amsoil, etc... and I would watch the oil and have it tested by somebody like Blackstone Labs at regular intervals to make sure nothing is wrong.