337 Oil Diluters.
 

Guys,

I was told a 1969 T337 had "oil diluters", which apparently were supposed to help the turbos. Has anyone ever heard of "oil diluters" on a C337? Could the man have been referring to pre-oilers?

Paul

On my 1968 it has a toggle switch area marked oil dilution. I have a section in POH about the use of the oil dilution for cold weather operation. I have never seen or heard of anyone using this feature.

That was a carry over from the radial engined airplane days. What you did was to hold that switch just before the engine was shut down on the previous flight, this would pump raw gasoline into the oil sump, diluting the oil. This was for preparation for a cold weather start, and you would get oil pressure earlier because the oil was thinner.

This was good in theory, but not in practice.

Thanks, guys! I learn something new each day...

Paul

Actually, come to think of it, diluting oil at engine start sounds like an awful idea - like they say, "The worst thing you can do to your engine is to start it...", because there's no real lubrication during the first few strokes, and those first few strokes account for something like 80% - 90% of cylinder/piston wear, from some figures I've read. For this reason, it's not recommended to pull the prop through by hand a few turns prior to starting, because this wipes off what little oil remains on the cylinder bores from the previous run, consequently increasing wear even further during engine start.

So to preserve cylinder/piston life, it sounds like a good idea to never use the oil dilution feature unless one REALLY needs it for cold starts. Any thoughts? Does one ever REALLY need it?

Paul

Well I suppose if you're in the remote northern or southern areas of the globe (or such), having a choice between getting the engine started and not getting it started could be a trade-off that you'd consider.

Oil dilution is no longer necessary if you are using 15w-50. Since the oil changes its viscosity; so it's thinner during the start and thicker when hot -- something they didn't have in 1968.

But, if you really want to limit the wear on the cylinders during start then you must use AVBLEND. There's nothing better then synthetic oil and AVBLEND -- and you should be able to fly the eninges 2000+ hrs.