Can you mix oil weights? [Archive]

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Ben Jackson

January 2nd 04, 08:50 PM

Let's say you're at a point where you need to add a quart of oil.
You've decided you would like to finish this oil change interval at
a lighter weight (eg you put in AeroShell W100, SAE-50, and now it's
freaking cold). Can you add a quart of a (substantially?) lighter
weight oil (presumably in the same 'series')?

--
Ben Jackson
>
http://www.ben.com/

Dave

January 2nd 04, 09:13 PM

Dave Stadt

January 2nd 04, 09:13 PM

"Ben Jackson" > wrote in message
news:CQkJb.261117$_M.1211945@attbi_s54...
> Let's say you're at a point where you need to add a quart of oil.
> You've decided you would like to finish this oil change interval at
> a lighter weight (eg you put in AeroShell W100, SAE-50, and now it's
> freaking cold). Can you add a quart of a (substantially?) lighter
> weight oil (presumably in the same 'series')?
>
> --
> Ben Jackson
> >
> http://www.ben.com/

Aeroshell says it is just fine to do so:

"All approved SAE J-1899 (former MIL-L-22851) and SAE J-1966 (former
MIL-L-6082) AeroShell oils are compatible."

Kyle Boatright

January 2nd 04, 09:35 PM

"Ben Jackson" > wrote in message
news:CQkJb.261117$_M.1211945@attbi_s54...
> Let's say you're at a point where you need to add a quart of oil.
> You've decided you would like to finish this oil change interval at
> a lighter weight (eg you put in AeroShell W100, SAE-50, and now it's
> freaking cold). Can you add a quart of a (substantially?) lighter
> weight oil (presumably in the same 'series')?
>
> --
> Ben Jackson
> >
> http://www.ben.com/

Absolutely. All aviation oils are compatible, and have to be to meet the
appropriate spec's. Otherwise, you'd be SOL if you needed to add a quart of
oil and the FBO on the airport you stopped at didn't carry *your*
brand/weight of oil.

KB

Ron Natalie

January 2nd 04, 09:40 PM

"Dave" > wrote in message ...
>
> "Ben Jackson" > wrote in message
> news:CQkJb.261117$_M.1211945@attbi_s54...
> > Let's say you're at a point where you need to add a quart of oil.
> > You've decided you would like to finish this oil change interval at
> > a lighter weight (eg you put in AeroShell W100, SAE-50, and now it's
> > freaking cold). Can you add a quart of a (substantially?) lighter
> > weight oil (presumably in the same 'series')?
> >
> > --
> > Ben Jackson
>
> why not just change the whole lot and do the job properly?
>
Shell says you can mix grades of AeroShell as long as both grades
are allowed for your engine.

Ben Jackson

January 3rd 04, 12:16 AM

In article >,
Dave > wrote:
>
>why not just change the whole lot and do the job properly?

Did I mention it's freaking cold?!

Heck, with the weather around here I don't even want to go to my Shell
distributor to get the oil, one quart or a whole case.

--
Ben Jackson
>
http://www.ben.com/

Mike Rapoport

January 3rd 04, 01:44 AM

Yes you can, but it might take a lot to make a meaningful difference unless
your engine is a big leaker.

Mike
MU-2

"Ben Jackson" > wrote in message
news:CQkJb.261117$_M.1211945@attbi_s54...
> Let's say you're at a point where you need to add a quart of oil.
> You've decided you would like to finish this oil change interval at
> a lighter weight (eg you put in AeroShell W100, SAE-50, and now it's
> freaking cold). Can you add a quart of a (substantially?) lighter
> weight oil (presumably in the same 'series')?
>
> --
> Ben Jackson
> >
> http://www.ben.com/

G.R. Patterson III

January 3rd 04, 04:03 AM

Ben Jackson wrote:
>
> Can you add a quart of a (substantially?) lighter
> weight oil (presumably in the same 'series')?

Yes.

George Patterson
Great discoveries are not announced with "Eureka!". What's usually said is
"Hummmmm... That's interesting...."

Dave S

January 3rd 04, 02:45 PM

heheh..

too cold to drive and get oil.. but not too cold to fly and burn it
off.. thats a die hard pilot.

Dave

Ben Jackson wrote:
> In article >,
> Dave > wrote:
>
>>why not just change the whole lot and do the job properly?
>
>
> Did I mention it's freaking cold?!
>
> Heck, with the weather around here I don't even want to go to my Shell
> distributor to get the oil, one quart or a whole case.
>

Skyking

January 3rd 04, 11:51 PM

(Ben Jackson) wrote in message news:<CQkJb.261117$_M.1211945@attbi_s54>...
> Let's say you're at a point where you need to add a quart of oil.
> You've decided you would like to finish this oil change interval at
> a lighter weight (eg you put in AeroShell W100, SAE-50, and now it's
> freaking cold). Can you add a quart of a (substantially?) lighter
> weight oil (presumably in the same 'series')?

The trick is to thin it with AvGas when you shut it down.

Skyking

Ben Jackson

January 4th 04, 12:27 AM

In article >,
Skyking > wrote:
>
>The trick is to thin it with AvGas when you shut it down.

Won't the gas all evaporate out the breather tube if you pour it into
the filler neck of a hot engine?

How much gas are we talking about here, anyway?

--
Ben Jackson
>
http://www.ben.com/

karl

January 4th 04, 03:30 AM

****How much gas are we talking about here, anyway?*****

My Cessna 185 has a factory option for an "Oil Dilution" system. There is a
table, seconds of OD push per temperature.

This was very common in the bush, and before reliable engine preheating.
Once the oil warms up, the gasoline evaporates.

Best,
Karl

G.R. Patterson III

January 4th 04, 08:18 PM

karl wrote:
>
> Once the oil warms up, the gasoline evaporates.

So it should be added to a cold engine just before start, then?

George Patterson
Great discoveries are not announced with "Eureka!". What's usually said is
"Hummmmm... That's interesting...."

J. Severyn

January 5th 04, 02:51 AM

"G.R. Patterson III" > wrote in message
...
>
>
> karl wrote:
> >
> > Once the oil warms up, the gasoline evaporates.
>
> So it should be added to a cold engine just before start, then?
>
Nope. Gas is added to the warm engine oil, just before shutdown. That way
the oil is diluted and thin for the next cold start. Pretty common on
radial engined aircraft.

John Severyn