Oil change.

I changed the oil in my O470R this weekend. 24.5 tach hours
and 4 months from the last oil change. I use AeroShell 100W+,
which is a 50 weight ashless oil (the one with the gold coloured
label).

After flying around for an hour or so to warm it up before draining,
I happened to notice that oil on the dip-stick is 'beading', rather
like raindrops on a window pane.

Am I right in thinking that this oil has wetting additives that have
boiled off in use?

Tony Cox wrote:
: After flying around for an hour or so to warm it up before draining,
: I happened to notice that oil on the dip-stick is 'beading', rather
: like raindrops on a window pane.

You're probably seeing some water condensed on the top of the dipstick
running back down. Burning gasoline results in some water being produced,
which eventually goes out the crankcase breather. Some condenses on the
top of the dipstick because it's probably the coolest point in the engine.

: Am I right in thinking that this oil has wetting additives that have
: boiled off in use?

I don't think it has such ingredients. Oil wets metal very well without
any assistance.
--
Aaron Coolidge

"Aaron Coolidge" wrote in message
...
Tony Cox wrote:
: After flying around for an hour or so to warm it up before draining,
: I happened to notice that oil on the dip-stick is 'beading', rather
: like raindrops on a window pane.

You're probably seeing some water condensed on the top of the dipstick
running back down. Burning gasoline results in some water being produced,
which eventually goes out the crankcase breather. Some condenses on the
top of the dipstick because it's probably the coolest point in the engine.

I don't see this with 'fresh' oil. Also, being blessed to live in
Las Vegas where the humidity is usually in the teens, it's unlikely
that there is any water contamination.


: Am I right in thinking that this oil has wetting additives that have
: boiled off in use?

I don't think it has such ingredients. Oil wets metal very well without
any assistance.

Any idea what the additives in 100W+ are, Aaron? I suppose
one day I ought to find out why I'm paying an extra $0.50/qt
over straight 100W. Perhaps that day has come!

Tony Cox wrote:

I don't see this with 'fresh' oil. Also, being blessed to live in
Las Vegas where the humidity is usually in the teens, it's unlikely
that there is any water contamination.

Read the response carefully. Burning fuel makes water. As a matter of
fact carbon dioxide and water are the predominant products of
hydrocarbon combustion (where do you think the hydro part goes ...)

"Ron Natalie" wrote in message
m...
Tony Cox wrote:

I don't see this with 'fresh' oil. Also, being blessed to live in
Las Vegas where the humidity is usually in the teens, it's unlikely
that there is any water contamination.

Read the response carefully. Burning fuel makes water. As a matter of
fact carbon dioxide and water are the predominant products of
hydrocarbon combustion (where do you think the hydro part goes ...)

You'll have to walk me through this Ron, because I still don't
get it. The flight to warm up the oil was just short of an hour.
I know that burning fuel creates some water & that it'll get into
the oil. But why am I seeing 'beading' in the old oil, but not the
fresh stuff? The only thing that can possibly be different is the
composition of the old oil compared to the new.

Tony Cox wrote:
: "Ron Natalie" wrote in message
: m...
: Tony Cox wrote:

: You'll have to walk me through this Ron, because I still don't
: get it. The flight to warm up the oil was just short of an hour.
: I know that burning fuel creates some water & that it'll get into
: the oil. But why am I seeing 'beading' in the old oil, but not the
: fresh stuff? The only thing that can possibly be different is the
: composition of the old oil compared to the new.

Did you wipe off the dipstick when adding new oil? Perhaps you've wiped
off the little bit of water that's condensed there.

I also see a little bit of water droplets on the top of the dipstick
depending on weather and flight conditions. Right after a flight there are
no water drops, but wait a couple hours and a few show up.

The "Plus" in the oil is the Lycoming antiwear additive required for
certain Lyc engines. It's probably a good idea in any engine (the additive
is an extreme pressure lubricant, I have been told, to minimize cam
follower wear).
--
Aaron Coolidge

"Aaron Coolidge" wrote in message
...
Tony Cox wrote:
: "Ron Natalie" wrote in message
: m...
: Tony Cox wrote:

: You'll have to walk me through this Ron, because I still don't
: get it. The flight to warm up the oil was just short of an hour.
: I know that burning fuel creates some water & that it'll get into
: the oil. But why am I seeing 'beading' in the old oil, but not the
: fresh stuff? The only thing that can possibly be different is the
: composition of the old oil compared to the new.

Did you wipe off the dipstick when adding new oil? Perhaps you've wiped
off the little bit of water that's condensed there.

Yes. Wipe, dip, check. Immediately after the flight. No water
to be seen. Instead of the oil adhering consistently to the
dip-stick, the old oil formed a sort-of 'river' up the stick leaving
some parts clear. It looked from the meniscus that it was
trying to form droplets. I should add that it wasn't just the
last flight before the oil change; the penultimate flight showed
the oil in the same condition too, now I think of it. It seems
that *something* that normally reduces the oil surface tension
had boiled off.


I also see a little bit of water droplets on the top of the dipstick
depending on weather and flight conditions. Right after a flight there are
no water drops, but wait a couple hours and a few show up.

The "Plus" in the oil is the Lycoming antiwear additive required for
certain Lyc engines. It's probably a good idea in any engine (the additive
is an extreme pressure lubricant, I have been told, to minimize cam
follower wear).

I've heard that too. I use it in my Continental at the suggestion of my
A&P whose opinion I respect. More expensive, so it must be better,
eh?

After flying around for an hour or so to warm it up before draining,
I happened to notice that oil on the dip-stick is 'beading', rather
like raindrops on a window pane.

Am I right in thinking that this oil has wetting additives that have
boiled off in use?

I don't think so. Seems to me that you had water in the oil.
I had it 2 weeks ago - first time. In my case I had the starter adapter
off for service and the engine wrqapoped in plastic.
AQfter my runup I n oticed the problem that you are having and took the
aircraft straight to the shop. They told me water in the oil - and as
the oil was new, go fly 45 minutes and it wouild boil off - which it did.

Tony
--

Tony Roberts
PP-ASEL
VFR OTT
Night
Cessna 172H C-GICE

"Tony Cox" wrote in message nk.net...


Any idea what the additives in 100W+ are, Aaron? I suppose
one day I ought to find out why I'm paying an extra $0.50/qt
over straight 100W. Perhaps that day has come!

The Lycoming anti-wear additive. Used to be TCP (Tri-Cresyl Phosphate)
until a few years ago when it was changed to TPP (Tri-Phenyl
Phosphate) when it became widely known that TCP was an extremely
neurotoxic poison that rapidly absorbs thru your skin. TPP is somewhat
less dangerous than TCP and works almost as well for protecting
against premature lifter/cam lobe wear.

Yes, this is the same TCP or TPP chemical that used to also be used as
a fuel additive to help prevent lead deposits from sticking the
valves, but has become virtually impossible to buy anymore.

You can now buy TCP through Alcor. www.alcorinc.com