Comment by drzaiusx11
10 hours ago
Oil in the exhaust in quantities high enough to produce acrid white smoke is extremely common on a number of ICE engines, like blown head gaskets on E25s (found in most Subarus before their Toyota involvement in 2010) for example
Subarus with bad head gaskets leak combustion gas into the cooling system displacing the coolant. If you run a flat engine low on coolant it will score the upper cylinder walls and the you will have oil consumption. This is fundamental to all flat engines. Oil in the exhaust is blue smoke. Coolant is white.
I never got the "blue" and "white" thing. Both look "white" to me, but you're right about subarus also leaking coolant in the exhaust which is easily identified by a "sweet" smell. Blown gaskets on ICE engines like E25s leak both oil AND coolant, no? I might be mixing up blown heads with cracked manifolds which often go hand in hand since temp extremes in engines fissure cast parts like the manifold. Either way the end result is the same: noxious fumes in the exhaust.