I was wondering if anyone else here has a Geo Metro and has experienced gigantic smoke clouds out the tailpipe when driving under load, especially freeway speeds. I recently picked up one of these small economy cars and understand this is a common issue. I was getting it bad until I gave me engine a good flush with Marvel Mystery Oil and Seafoam. It appears to be solved now so I guess I either cleaned up some stuck rings that were causing excessive blowby or there was crud I cleaned out of the oil drainback holes in the head. It was puking oil through the PCV line back into the intake and I had just changed my PCV.
I am on a Geo Metro forum and this appears to be a common issue. The term commonly used is “oil farting”. If you have one of these cars and are experiencing this, you might try a good flush of the engine before considering junking the car or rebuilding/replacing the engine. I let some Marvel Mystery Oil soak in the cylinders overnight too.
Be ready to change the oil and filter after doing this flush as it will get REALLY dirty and nasty really quick. I drove the car maybe 20-30 miles with some MMO and half a can of Seafoam in the crankcase.