Urgent Help with 1999 Pontiac Grand Am

[bigalpha]

Posting up to help a buddy.

1999 Grand Am
85,xxx miles
Loud knocking from engine
Does not leak oil onto ground
No oil in antifreeze
Does not overheat
~30% gas mileage reduction
Has to add oil to engine
Engine oil pressure gauge reads "normal"
Mechanic said knocking was coming "from upper internal part of engine"

Apparently, someone told him those car engines have a ~10 year life span.

I don't know anything about Pontiac engines and I'm about 2.5 hrs away. Any quick ideas to try? Seafoam? Sensors? or is it really fubar?

TIA

 

[GrimmJeeper]

loud knocking is bad. has it been using oil for a long time? sounds like maybe a piston is worn around the wrist pin or maybe the rings on one or more pistons has either siezed into the groove on the piston or broken. pull the plugs one at a time and see if any of them are oil soaked or covered in carbon, if so you have a problem in that cylinder.

 

[bigalpha]

Don't think that it's been using oil for a while. It's been a solid running car up to this point. I'll pass along the tips about pulling the plugs.

 

[CanMan]

V-suck or 4 banger?

 

[bigalpha]

lol, It's a V6. I thought I edited my post to say that, guess not.

 

[kastein]

blew a connecting rod bearing maybe? Just happened to a friend of mine's Celica, apparently it's a common failure on the 5S-FE engine.