has anyone with a heavy oil burning (1 qt. 600 miles) m103 engine also had a warm engine hard to start condition?

If you are burning oil and the car is hard to start I would pull the spark plugs and check them for signs of oil. The loss of oil could be because the oil is leaking into the cylinder and the cylinder is burning off the oil and the time that the oil is settling it is leaking on the spark plugs, thus making the car hard to start. Especially if the engine is warmed up because the oil has been circulating in the valve cover which may cause fresh oil to leak past the seals and onto the plugs soaking them. Check plugs for signs, most notably they will either be wet with oil or have ash-like deposits on them. You can also check for blue smoke coming out of the tail pipe when you start up the car and press the gas pedal. This is caused by worn valve stems which will need to be replaced.

First picture shows charred ash deposits on plugs from oil or poor quality fuel
Second picture shows oil coating
Third picture shows what the plug should look like with normal usage.

Cheers!

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1990 190E 3.0L

I ran a 300E for several years that used engine oil, noticeably above 3000rpm / 70mph, but it did it from new and continued, annoyingly, until 110000miles when it was sold. It did not have hot starting problems though.
The most likely culprit was the valve stem oil seals.

you can put oil burners on the plugs they will sheild the plugs

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1999 w140, quit voting to old, and to old to fight, a god damned veteran, deutschland deutschland uber alles uber alles in der welt

This may be true, but he will still be losing oil.....and in the long run, will possibly gunk up cylinders and catalytic converter with carbon deposits and ultimately fail smog.

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1990 190E 3.0L

Valve stem seals are leaking and thats why you are burning a ton of oil.

Hard to start could be a separate issue assuming plugs are not fouled.

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Agree. Do you know if they have ever been replaced? The seals are cheap. IIRC, when my 88 CE started burning a qt every 500 miles or so back at about 75,000 miles (2004-2005?), the job cost me about 200 USD parts, labor & sales tax at an indy..a good one.

My 103 burned about that much oil on the highway from the day it was built, until the valve stem seals were replaced - no more problem for the last 23 years.
I fought a hot-start issue for years; changed everything; finally the 3rd set of injectors fixed it after 15 years.

DG