NEWBIE I have a 98 12v automatic. 258-9k, #100 fuel plate halfway way forward, pump turned 5 clicks. Intake, Exhaust, Fully built goerend. Background: When I bought it with 250k it had zero smoke puffing out of the oil fill. I just checked for the first time after buying the truck after 10kmi. The only thing been done since then is the tranny and pump tune, and I had the oil changed once, the shop did it, I do not know with what. I checked recently when adding oil (mystic 15/50). It used a little less then a gallon over 8kmi. But i'm not sure if that's due to a slow leak or burning it. During cold weather (below 35f) (although it was in the teens earlier that night), it has trouble starting it will crank right up and die a second later, on the second attempt it starts up and idles very low, by the time I get out of the parking garage it is warmed up fine and idles at 750, and 600 in gear. Blowby: after it is warmed up it puffs with the idle enough to plainly see. I checked underneath for the breather but couldn't find it and didn't see any smoke exiting below the truck, only out the oil fill. I did the cap test, it does not blow it off, it does not spew oil, I can barley feel it against my hand, after a long run, it does it a little out of the dipstick too. I recently fixed an exhaust leek right after the turbo by tightening the bolt, but it sill poofs a little, very very little, when revved. The oil pan is dry as a bone on the outside. Haven't looked into it much further. But this is my daily driver/baby. ---AutoMerged DoublePost--- Please, any input, and redirect me if need be. I'm pretty concerned at this point.

sounds normal to me.

that was the response I was hoping for. I've heard both that this is normal and that it is something to worry about. If anyone else has some input the more the better.

Yes, your engine sounds good to me A little smoke exiting the oil fill cap when warm is normal. As long as it's not heavy smoke, which it sounds like it's not, and it does not bounce the oil fill cap when you just set it resting on the top, which in your case it doesn't bounce. There is nothing to worry about.

That's good to hear. It puffs about at much as my dad's 317kmi 7.3 psd. It's not a whole lot but it is more than a little. Probably about a small golf ball sized puff each time, like I said the oil fill cap stays put. Is there anything I should start doing? Thicker oil? or anything like that. Unfortunately I don't know what is in it now, but it has at least a gallon of 15/50 mystic in it. It only puffs after I have been driving or idling for at least 10 mins.