You cannot tell the condition of the oil by visual inspection, unless of course it is heavily contaminated. Do it by mileage, time or oil sample.

 

When I got my S&S 111" I noticed that they did install a drain plug in the bottom of the crank case. I thought that was pretty cool. I like being able to drain all my oil. But I agree that it isn't necessary. Nice yes, but necessary, no.

 

If you drain all the oil out of your crank case does the lack of oil (until the pump can fill it) cause any harm the first time you start it up after oil change?

 

Here is somthing that blew me away .,
After some research i found that the aviation industry does not adhere to timed oil change intervals. They instead regulary test the oil for contaminates etc. I assume this to be a cost saving procedure .?
Anyone else ever heard of this ?

 

I thought they went by hours the engine has run.

 

It would not hurt a thing for no oil to be in the crankcases on startup.

The oil that is laying in the bottom of the crankcases has already gone through the pump, lifters, rockers, crankshaft etc.

The next thing that happens to that oil is when the pistons come down, the oil gets blown into the cam chest and is picked up by the scavenge element of the pump, and it is pumped through the oil filter and back to the tank.

 

It depends on the engine. Small air cooled reciprocating engines are done by time intervals. Engines that do not have oil filters are done every 25 hours, and 50 hour interval for engines with oil filters, if I remember correctly.

Large radial engines consume so much oil that oil changes are not necessary unless oil sample or chip detectors indicate a need.

On large jet engines (my bread and butter for the past 41 years), oil is not changed unless an oil sample indicates a need (rare).

I can`t say how it is done on small jet engines, I don`t work on them...

 

I'm not an engineer, but I would think if there were any such concerns, S&S wouldn't have put the drain there. We all know they don't want warranty claims.

It’s all based on tach time. Analyzing oil is typically done on high-time and over-time engines.

 

ok some of you probably know this..
this is for the ones that don't there is always oil in the crank chamber its not blown out by the pistons coming down. it is slung by the crank to the oil collector at the top of the case (red circle) then drains into the cam chest where it is scavenged by the pump. there is anywhere from a pint to a half qt depending on the crank clearance to the case in the crank chamber all the time.


and some high performance cases do have what looks like a drain plug in them and can be used as one. but its for an external scavenger having a crank sling oil robs HP.
its kind of like putting a windage tray on a small block chevy.

 

In the commercial and military aviation world, oil is analyzed from the time the engine is new until it goes to overhaul.