Despite your extensive efforts to fix this problem, it appears you still have a situation where the coolant and oil are mixing. No oil should be able to mix with the coolant (or vice-versa) and if it is (which is why you’re seeing oil in the coolant tank) then you have a fairly major problem somewhere in the engine. Check the dipstick. Is the oil in the sump milky and opaque? I’m guessing it probably is, and that’s another giveaway that your engine has a major problem.
Perhaps the cylinder head itself is cracked. Maybe the engine has a split bore. Perhaps the light skimming the head received was not enough and it’s still warped. Either way, the oil and coolant are mixing and that’s bad. The fact that the oil and coolant in the bottle are being forced out of that tank suggests combustion pressure is also playing a part, once again signalling a leak between the oil, coolant and combustion areas of the engine.
