99 Civic Oil Loss

[Kirk2]

I have a 1999 Civic DX (manual trans.,98,000 miles) that is losing a quart of oil every 600-700 miles.I use the Civic on a daily newspaper delivery route that is approximately 80 miles in length with 400 plus stops.Of course,this involves alot of upshifting and downshifting between stops.The car generally runs strong,with just a slight loss of power noticable since I purchased it 35,000 miles ago.I am seeing no oil on the plugs,no visible oil leaks on top of or underneath the engine and no smoke out of the tailpipe,although the inside of the tailpipe is very black and sooty.Also,I had the valves adjusted approximately 25,000 miles ago.What are some of the possible repairs I could be looking at?I know I am probably reaching,but could something as minor as the valves needing to be adjusted again cause this?Thanks so much for your time and help with this.

[superbluecivicsi]

generally, a quart per oil change (every 3500 miles or depending on driving condition is the norm).

if its not leaking or burning, then it must be going somewhere. i would say recheck it. a compression test and a much more closer look at the oil pan, head gasket, vtec selonoid, distributor, oil pressure sender, and oil separator box.

[bluevp00]

my 2000 DX with the same engine burns oil too. I have 102,000 miles, but I only burn about 1 quart every 2000 miles though. I asked a mechanic and he said to use a thicker oil, he recommended 10W-40. I tried "Restore" brand oil treatment (comes in a sliver can) it seems to slow the oil burning down a little bit too.