My truck just started doing this thing where it won't start- it tries to turn over, but it's like it wants to seize. I checked the oil- it was a little low but not where it should stop everything. I added to it and it still isn't any different. The fuel pump/filter (and I can hear it pump when I turn the key) are fairly new, starter is newer. I also replaced plugs and wires fairly recently. I don't know what else to look at. I'm hoping it won't be completely seized but I really can't tell.

 

Maybe a tired battery??