Non-dispersant aircraft oil?

[speeder]

Anyone know what this means? I figured out that dispersant is something that is used to clean up oil spills in bodies of water, is it normally added to aircraft oil?

The reason I ask is that I have a friend who is rebuilding a motorcycle and I told him to use non-detergent 30w to break-in the new rings. Instead, he found some aircraft oil that is pure mineral oil and "non-dispersant."

I'm confident that someone here can end my confusion.

[otto_kretschmer]

I'll take a stab..

if I remember right...

dispersants are used in oils to keep contaminants in solution, or to keep the contaminants suspended in the oil. If they are not suspended then they will collect in the pan and pockets and form sludge.

A non-dispersant oil for break in shouldn't be a problem if the oil is only used for a couple hundred miles and then changed.

But if he has a motorcycle why not use a motorcycle oil? Using an avaition oil in a motorcycle reminds me of some guys using a car tire on a motorcycle.

It may depend on which motorcycle he has. If he has a newer bike with a wet clutch, he may have problems with the clutch slipping. Motorcycles with wet clutches need oil with the JASO MA/MA2 rating or the older SG/SH. If he has an old BMW or Guzzi with a dry clutch and solid lifters he will need an oil designed for solid lifters (SG or SH).

[Tim Hancock]

I was taught to always run mineral oil in aircraft engines for break-in. It allows the rings and cylinder walls to make metal to metal contact at any high spots. If regular oil was used during this time, the cross hatching could glaze over thus preventing the ring seating process. After the first 50 hours of running engine hard, we switched to ashless dispersant oil for normal continued operation.

Here is a link that explains the reasoning as it relates to aircraft engines.

https://www.shell.com/business-customers/aviation/aeroshell/knowledge-centre/technical-talk/techart08-30071255.html


Some of the oils I kept in stock when I ran a side business working on aircraft.

[speeder]

OK, thanks. Why straight mineral oil for aircraft engines?

[Zeke]

Originally Posted by speeder

OK, thanks. Why straight mineral oil for aircraft engines?

I thought he explained,

Originally Posted by Tim Hancock

I was taught to always run mineral oil in aircraft engines for break-in. It allows the rings and cylinder walls to make metal to metal contact at any high spots. If regular oil was used during this time, the cross hatching could glaze over thus preventing the ring seating process. After the first 50 hours of running engine hard, we switched to ashless dispersant oil for normal continued operation.

Here is a link that explains the reasoning as it relates to aircraft engines.

https://www.shell.com/business-customers/aviation/aeroshell/knowledge-centre/technical-talk/techart08-30071255.html


Some of the oils I kept in stock when I ran a side business working on aircraft.

[otto_kretschmer]

Originally Posted by speeder

OK, thanks. Why straight mineral oil for aircraft engines?

Aircraft engines like Lycoming and Continentals are 1940s technology and they really haven't changed much. They don't have cat converters or variable valve timing. They may not even have O2 sensors.

1940s engines need 1940s oils maybe.

so what bike does your friend have?

[LEAKYSEALS951]

Originally Posted by otto_kretschmer

so what bike does your friend have?

[Bill Douglas]

Originally Posted by speeder

OK, thanks. Why straight mineral oil for aircraft engines?

Maybe because they don't have much of a variation in rev's and the engine temperature doesn't change as much as a car or motorbike.

[Indescikov]

You don’t really want dispersant oil if there no oil filter to capture the particulents..
Older aircraft engines do not have oil filters, usually only screens to capture the “big” parts.
Oil filters were a later development and often can be added to older engines under approval from the FAA. That would be a STC. Supplemental Type Certificate.

[dar636]

It is used for initial break in only. Once oil consumption stabilizes you would switch to non-mineral oils. 5-10 hrs .

[Jrboulder]

A big problem with aircraft engines is leaded fuel, certain combustion byproducts basically make running a full synthetic impossible. Mobil tried with AV-1 and it was an absolute disaster. Also, many aircraft owners are the world’s biggest cheapskates and won’t pay more for an advanced additive package.

Basically not a good oil for anything but flying lawnmowers.