Straight wt oil getting hard to find

2 applications I can think of are the old Donaldson air breathers with pre-cleaner jars and engines that have sump pits, splash lube lube systems with a deep sump under the crank and bearings. The old vertical 2 cyl. 24 HP Cat starting engines are built like this, having 2 deep sumps underneath. By design I assume the oil would settle out the contaminants, but this little screamer of an engine has inspection covers that allow access to clean out those sump pits, and once clean, either oil would be fine, modern probably better. I tore down an old 14hp Kohler K321 from the late 60's not too long ago and the oil pan was heavily sludged up, but you could still see the cross hatch on the cylinder walls.

I can see some validity for non detergent oils in those air breathers as it would settle out, vs suspended but does one or the other still perform better in that application.

This would make a good "Myth Buster" theme, take an old gunked up engine and see what the det. oils do.

This is like the battery on the concrete myth.

• Hobby farm

Straight weight none detergent oils begat sludge. Further the heavy oil means poor lubrication when starting and running cold. The lack of anticorrosion additives guarantees pitting of the crankshaft as well as the cam shaft and the bearing inserts from moisture and sulfur in the oil. In the 40s engines lasted 30,000 miles between rebuilds on straight weight oils. Now the computer dies at 200,000 miles or the body rusts off and the beearing technology isn't that much different, but the oils are DIFFERENT!

If an engine is sealed only by sludge on shafts, then the oil passages are already plugged by that sludge and lots of parts aren't getting oil. Changing to a detergent oil isn't going to make that sludge in the passages worse, in time it might improve it. So when changing to that detergent oil it might be a good idea to change oil and filter more often to remove the sludge. Detergent oil should hold the sludge (and unless an engine has been run without an aircleaner in sand the sludge should not be abrasive) in suspension or solution until its drained.

So why do you want to abuse your engine plugging the oil passages and corroding the bearing surfaces when you could clean and protect it with modern oil?

Gerald J.

If you have been using non detergent oil I expect a lot of crud is built up in there and the High detergent oil will cut it loose and plug passages and such.

steveormary