It's true that the old VW engines only lasted 80-90k but I don't think it was the lack of oil filtration that killed them. Being air cooled, they ran at more extreme and less uniform temperatures. They were also very underpowered and forced to run at full throttle for much of their life. I am sure the lack of oil filtration didn't offer any benefits but there are other factors to consider as well.
If oil filtration has a big impact on engine wear, wouldn't the use of bypass filters extend the life of the engine significantly? I don't know. Perhaps someone can offer some evidence to support this.
If oil filtration has a big impact on engine wear, wouldn't the use of bypass filters extend the life of the engine significantly? I don't know. Perhaps someone can offer some evidence to support this.