Originally Posted by JCL

It may help those new to this issue to know the failure mode for the oil separator. The oil separator failing doesn't cause the problem. Primetime outlined this above, but here is a bit more detail.

All engines get condensation inside them, worse in cooler weather. When you get the engine good and hot (30+ minutes, preferably more), the condensation burns off. If you only do lots of short trips, it never burns off, and it builds up. It forms a milky paste that is visible under the oil filler cap. If you don't have this build up of condensation, the oil separator is not going to be an issue until the rubber hoses go soft, usually in 5 years or so (similar to rad hoses).

If you drive for long enough with the condensate building up, it collects in the oil separator. Still no problem.

Now, if you have that buildup, and it gets very cold, the condensate can freeze in the separator (since it has water in it). That is what is being referred to as the separator failing. It isn't really failing, it is just freezing. It isn't even freezing itself, the gunk inside it is freezing.

The insulated separator has a higher tolerance for low temperatures before it freezes, but it doesn't solve the problem (the condensate), it just tolerates colder temperatures. Personally, I have never had a separator freeze (even in -30C), but then I don't tolerate lots of short trips as that is very hard on the vehicle.

Even if you have the new and improved separator, it is worth checking the separator every few years (not sure what interval is right for each individual) to see if condensate is building up there. If so, clean it out. That is the best preventative measure, even better than putting the new design parts on. Eventually the separator will fail (rubber goes soft) and then it is a toss up if the new and improved one is worth doing or not. Can't hurt.

Hope this helps those who are trying to figure out what to do after an OSV freeze up.