All right, I thought I was somewhat knowlegeable, but this one's got me stumped. I have an 89 F-250, 460 EFI, C-6 transmission, 410 gears. Bought it with 45000 miles on it a couple of years ago. Always ran great, but used a quart of oil for every 100 miles or so. No leaks, plugs showed a good bit of oil fouling and an exhaust analyzer showed a lot of smoke (no visible smoke though). Also lost a bit of antifreeze, never could find where it was going either, assumed a leak I couldn't find. Compression was good on all cylinders so I figured that as little as it had been run, maybe it had a rusted cylinder or a broken oil ring. I didn't have time so for the first time in my life I had a shop rebuild it. I found a good reputable shop and let them have at it. Put in flattop nominal 8.9:1 compression hypereutectic (sexy coated skirts as well) pistons, the only emissions legal performance cam I could find for the speed density 460 (CompCams PN 34-255-5), and topped it off with the Banks Powerpack exhaust and a high flow performance catalytic convertor. Now power is great, response is awesome, but I still use a quart of oil every 300 miles or so, and antifreeze problem is still there. We've gone over it time and time again and all we've found is a bad EGR, I'm replacing it now but I don't see how that can cause an oil consumption problem, let alone the antifreeze thing. Pressure test on cooland system is tight, and leakdown test shows perfect in all cylinders, as does compression check. Any ideas anyone, please?

Thanks in advance,

truckpilot