1992 m50 non vanos burning oil

[Nighthound198]

My car burn oil...like crazy. It’s the m50 non vanos motor. Anytime I get into the throttle it bellows blueish smoke, at idle it will puff out exhaust and even when there’s no blue smoke it constantly smells like there is. I’ve looked around but nothing seems to be a solid awnser or direction. Could it be most likely rings? While driving down fairly steep hill in 5th gear it can hold 80km so I’m thinking it’s got good compression in cylinders (only kind of test I have access too unless I buy it) or could it be valves? Mabe a tuning issue idk any help is appreciated next step is just rebuilding the whole thing which I don’t have time for l, just trying to get an idea what the best direction of the issue is or if I have to go buy test equipment to figure it out. Thanks

[ross1]

poorly sealing rings usually manifest as you describe, smoke on throttle up and at idle too if really bad. Worn valve guides or seals will pass oil in high vacuum conditions as when lifting off the throttle from cruise. Worn valve guides/seals also will cause the engine to smoke on start up as oil has seeped past while the engine was at rest.
DON'T discount the possibility of oil being introduced by the crankcase ventilation system.

[Nighthound198]

So from what I’m understanding biggest chances are bad piston rings and valve seals possibly valve guides as well

[ross1]

My big caveat at the end was to check the crankcase venting. If it is sucking oil through the intake it would explain everything.
These are pretty robust engines that commonly go well past 200k miles. How many miles on yours?

[koole39]

Nighthound... ross1 is absolutely on target on checking the crank case ventilation valve system. When was the last time it was changed on your 1992 bmw?

FWIW, I changed mine last week on my 2002 530i (caution: one of the more complicated DIY projects). The hoses to these systems are made of plastic which leak and crumble over time (dont know why BMW would not do this all in metal given that high temp oil vapors that go into this system). My hose from the CCV valve down to the oil pan had a broken gash from where oil was seeping out. In addition, my CCV return hose to the air intake manifold was pushing oil (hence oil consumption). Basically my CCV valve system had failed due to age, thermal wear etc.

New CCV valve with new hoses makes my car ride like it was new... smooth, no rough idling at start up, fast acceleration.
I am watching the oil consumption in case there is another source as well but so far so good.