I had a 1990 2500 pickup, with 6 lugs. It was a 350/ automatic 4X4. I had a "condenserator" installed. It was an exhaust gas, or crankcase gas filter, recycler. Im not exactly sure how it worked, but my mileage went up from 13 to 17, and the throttle response and power seemed to increase. I now have a 2000 k2500 with the 5.7. I sure would be interested in getting another one. Anyone know anything about it?
I have no idea what this "condenserator" thing you mention is. Air pressure in the crankcase is relieved through the PCV system, which is standard, and an emissions system requirement, on all cars and trucks. I don't know what it would do with exhaust gas, if it wasn't a turbocharger.
There seems to be some references to a "Condensator" branded thing, which is just a desiccant jar in-line in the PCV hose that runs back to the intake. They seem to have been priced at ~$170, and their web site is now down (probably because it was a huge scam). You could buy a $3 air compressor hose in-line desiccant valve at Harbor Freight, and install it in-line in the PCV line, and it would do the same thing.
It might help a little, but if it helps as much as you claim it did, there was probably something wrong and your engine was dumping plenty of oil back into the engine through intake via the PCV hose.
While driving more efficiently and maintaining your vehicle will help you improve the fuel economy of your car or truck. Make sure the tyres are inflated at the manufacturer recommended levels.This will help to you to get better mileage.