Lehman 120 blue gray smoke

[RedRascal]

Looking at a boat with a 120 Lehman with somewhere between 3,500 to 4,000 hours on it. No record of a valve adjustment, injector R&R or injector pump rebuild. Did not see engine cold start but saw it start after sitting about 4-5 hours after it's first start of the day which was just idling at the dock. Engine was probably 100 degrees when I saw it start for the second time and blew a blue/gray smoke cloud about 20' x 30'. Enough to gas out any neighbors sitting in their cockpit. After about a minute the blue went away and settle with the gray output in the pictures below. Since the engine had already ran earlier, would it be expected to see blue smoke? I thought oil leaking past the valve guides from sitting would have been burnt off with the first start so new blue smoke 4-5 hours later seems like oil is leaking past the valve guides in a short amount of time. So is this an issue to be concerned about or is there another source for the blue smoke? I am assuming it's not the rings since it stopped after about a minute. I am assuming the gray is a combination of cold engine and questionable efficiency of the injectors and pump at current service level. The blue is what concerned me.

 

[Lepke]

Blue smoke is oil. Valve guides usually don't leak much. I think rings. Most engines as temps rises causes the rings to seal better. If you are looking to buy, I'd do a compression check. If compression is ok, I'd check the injector tips. Changing oil might help.
If the engine idled for long periods, I'd suspect a lot of diesel in the oil. It has been shown that the lower combustion pressure of long idle times doesn't make the rings seal as well so more fuel washes into the oil. Lightly diluted oil helps carry the oil past the rings. Rings are designed so that combustion pressure forces them against the cylinder walls.
There are a number of studies of idle times combined with oil tests showing long idle times put diesel into the oil. It's better to warm the engine for a short period, a few minutes, and then go.

 

[Mainecoast]

Looks about average for a Lehman....once it warms up to operating temp and under load, it should clear up substantially.