Interesting Blue Smoke - Blow-By?

[bustedbenz]

I've got a curious symptom that I only recently became aware of after switching to a parking lot I never used to use here at school - important to my question is the fact that the parking lot is at the top of a rather long medium-steepness hill.

Rather than riding the brakes all the way down the hill (probably a good four or five tenths of a mile coasting down hill) I usually just use engine braking - downshift into 1 or 2 and coast that way.

When I do a cold start, (cold is defined here as the engine being nominal 50 degrees ambient) and coast down the hill - there is no smoke as long as my foot stays off the accelerator. However, when I'm going down the hill, if I accelerate even slightly - just enough to switch the engine over from "Holding" the speed down to "making power" - I get a puff/cloud of blue smoke out the back which, I understand, is Rotella. If I keep accelerating, after the initial cloud passes the smoke stops. If I go back to coasting/engine braking for a few more seconds, and then accelerate again, I get another cloud of blue smoke.

Here's the interesting part... if I do the same descent after the engine is up to operating temperature and has been driven for a while and gotten good and hot, the symptom completely disappears and I'm back to just little whiffs of diesel smoke once in a while just like normal.

Could this be oil being blown through into a cylinder under the "pressure" of engine braking and then combusting the first time that cylinder starts making power again? It never does it just going stop light to stop light on level ground, the added strain of holding 1st gear going downhill for a prolonged time when cold seems to be the ONLY way to create this symptom. Wondering if maybe it's oil blowing through a ring that gets cold and dry when the car is parked for a week at a time in cold temperatures, and then that ring gets warm and lubricated again and starts to seal more properly.

How much trouble do I have? It seems to run fine... but it's a new symptom. I'm willing to believe the thing is starting to get somewhat worn out, it's got over 200,000 miles on it but we don't know precisely how many. Never been rebuilt or dismantled further down than the valve cover gasket.