I run my truck @ 1500 alot,and unless I've got some uphill it don't usually get to 900*
Sometimes if the outside air temp is low,and my truck is cold I can get some high EGTs,I think it's trying to get the molasses in my rear axle moving.

 

It doesn't defuel at 1500rpm's, it is set on my box to defuel at 900 because of the post turbo probe. Figure it is about 1200 at the manifold when it finally defuels.

Does the post turbo probe really have about 250 degree diff than pre turbo?? And do you add 250 to all temps or just on the higher temps??

If i gear down I will be running in 4th all the time.

 

have you checked intercooler for oil buildup?
when mine was getting warm i had about a 1/4 inch of oil built up from the fan blowing it into it

 

Was me I would buy a 1/8 pipe plug and stick it in that hole were the probe is now and drill and tap it pre-turbo.

Then you can set your de-fuel limit at 1,200 or so.

As for the oil mist... Get rid of that stock crankcase vent... (Breather bottle) you might want to build my simple idea...
https://www.dieselbombers.com/5-9l-2...vent-bomb.html

 

I was going to wait on a new BD manifold and then move my probe. I know this doesn't fix my problem now but shouldn't be to long.
I also drain my breather bottle every oil change. I haven't noticed any oil on the radiator or intercooler?? Will double check.

Great idea on the vent though.

I'm going to order a new set of intercooler boots next week for a peace of mind. Thought I heard i little low howling???