Oil in air intake - Banks turbo

[Frank M. Hardcastle II]

I have oil in my air intake on top of my motor. The only place it could come from is the turbo. Mechanic yesterday replaced AC11 glow plugs with AC60 and replaced the glow plug controller and glow plug switch/sensor. I had it run to a switch on the dash just after I bought it 2 years ago because it came on all the time even during the heat of the summer after the engine had been running for an hour or so. Finally, The dash light quit coming on 2 days ago and the truck wouldn't start unless I plugged in the block heater to an extension cord. Figured it had finally given up. Well the mechanic told me I had cut the wire with the emergency brake somehow and he fixed it. Well I had already bought the above parts and figured some if not all needed to be replaced anyway due to the previous problem with my hyperactive glow plugs so I told him to go ahead and replace them that way I wouldn't have to do it later. While there in there I asked about the oil in the air intake on top of the motor. The mecanic said he thought the seals on the turbo needed to be replaced and that in order to get to the back two glow plugs on the passengers side he would need to remove the turbo. He said he would also need a new gasket for the turbo when he reattached it. Waiting to here back from Banks on the cost of the parts. Really would like to know if this sounds right. My fuel mileage has been around 13 mpg even after I put in a 3.54 rear end and a NV4500 5 speed. Seems low to me. I've noticed that it uses about a quart of oil every 3000 miles. If its burning the oil that might explain the oil usage and maybe the fuel mileage (thats a guess, please feel free to chime in). He also said he advanced the timing one click. I don't know what that means but the truck sounds and runs the same. Am I in for trouble? Please share your knowledge because I don't have any.
Thanks for taking the time to read this.
Frank