(quoted from post at 14:44:41 10/21/16) At the risk of sounding like a teen ager, I need to ask a question. As will become immediately apparent, I don't know Diddley, about a diesel engine. This truck was bought 5 years ago, and has sat in my back lot for 4 of those years. The first year It was in the shop ( one guy, or another ) No one ever cured my excessive oil useage, but I parked it after $6000.00 in repairs. One shop pulled the engine, and put in new front and rear seals, and pan gasket. When I got it back the last time I drove a 60 mile round trip, to pick up a deep freezer, and used over a gallon of Rotella 15-40. One guy told me that fords didn't have a turbo on their 7.3's in 1990, and the one on mine must have been an add on. The same guy said that the oil was being burned because of the turbo seals. In the beginning of this debacle, I had my mechanic give it a compression test, and he said they are all good, so therefore I started to look for other causes. The truck still (today) starts good, and runs down the road good, but often will leave a white cloud behind me. Can I delete the turbo, to see if that helps?? I still am on the first tank of fuel, from 5 years ago. I am afraid to use it. It is a 1990 Ford superduty 350 dually, and I need it as a trailer puller.
I am far from an expert, but I'm an idi junkie, so to speak.. Both of my trucks have a 7.3 idi (one was originally a 6.9, I swapped a 7.3 into it).
The turbo is not factory for a 1990. It is possible in its life it had a engine from a 1994 swapped in (which would have been factory turbo), but most likely it's a ats or banks kit.
Turbo seals could be a possibility for your oil consumption, but could be valve seals, or could still be bad compression, depends on how familiar with diesels the shop that checked it is. Without looking in the book I believe that the idi engines are supposed to be in the 2-400psi range, and I believe the factory turbo idi's range starts at 50 psi less (again, would have to check my book).
The white smoke could also indicate injection pump issues (but with the amount of oil you are consuming, it very well could be oil smoke). My daily driver is on the "tired" side, and I have no idea how many miles are on the engine/inj pump, but roughly a year ago it started smoking bad, but no increase in oil consumption. Had injectors pop tested, they were all ok. Tested compression, all within spec, checked everything I could think of.. Stumbled upon a diesel truck forum where a poster had similar issues, his starting after a pump swap, they told him to try advancing the pump timing, to which fixed his. I tried it on mine and what a world of difference. Someone will come along and post that if the pump and pump housing marks are lined up its in time, but that is only true if it is the ORIGINAL pump to that engine.
My suggestion for your consumption of oil would be firstly to remove the tubes on the intake side of turbo and check for signs of oil.. If you're using a gallon in 60 miles there should be signs that oil is blowing by the seals. I would also do a compression test myself, they're easy enough to do, pull one glow plug at a time and crank. I leave the key off and jump the solenoid on the firewall). I believe O'Reillys rents a diesel compression tester, or harbor freight sells em cheap (but the Ford/Navistar idi adapter won't thread into the hole, at least mine wouldn't).
IF YOU DECIDE TO REMOVE THE TURBO KIT, I WOULD BE VERY INTERESTED IN PURCHASING IT FROM YOU.. DON'T JUST TOSS IT IN THE SCRAP PLEASE! All you should have to do to do away with it is remove the turbo and all related plumbing, buy a "factory" y-pipe, and factory style air filter (I have a couple extra filter canisters I'd spare for the cost of shipping), and plug of the oil supply to the turbo. The pump may have been turned up for the turbo, but I wouldn't think it would be turned up to the point of excess fuel smoke without it, but even so, the pumps are easy to "back off" the fuel.
My email should be open if there is anything more I can do to help, I'd like to see you get the old girl straightened out.
Brad