Out Dated Turbine Oil

Graueradler

Graueradler

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Graueradler
I have two cases of out dated turbine aircraft engine oil. Anyone know what it might be good for other than turbine aircraft engines?
 
Why does turbine oil have a "best used by date"? What goes wrong with it?
 
Graueradler said:
I have two cases of out dated turbine aircraft engine oil. Anyone know what it might be good for other than turbine aircraft engines?
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I wonder if it can be used in a part 91 turboprop aircraft?

If not, I'd look for someone heating a hangar with drain oil.
 
I always offered my old petro products to an A&P with a diesel engine either in their truck or farm equipment.
 
Rotor&Wing said:
If you mix turbine oil with a petroleum based oil you will get jello and some very bad results. Turbine Oil is a pure synthetic.
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I've beem trying to figure this statement out...Some synthetic oil contains esters while others are made from condensing (polymerizing in this case) olefins into a longer alkane chain in a fashion that produces carbon chains of a controlled length. Both of these are miscible with mineral oil (term used to describe petroleum distillate). Semi-synthetic motor oil is a mixture of mineral and synthetic oil which works well in cars.

I'm not saying that the oils should be mixed in aviation applications- whatever instructions for the engine/transmission/oil should be followed to avoid bad things.

I'm just curious about the gelling mechanism mentioned. Is this something personally observed?

flyersfan31 said:
Homemade Napalm????
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Maybe that's what you get! Considering the higher flashpoint and low vapor pressure of oil, I'm not sure how well it works compared to gasoline.
 
Cap'n Jack said:
I've beem trying to figure this statement out...Some synthetic oil contains esters while others are made from condensing (polymerizing in this case) olefins into a longer alkane chain in a fashion that produces carbon chains of a controlled length. Both of these are miscible with mineral oil (term used to describe petroleum distillate). Semi-synthetic motor oil is a mixture of mineral and synthetic oil which works well in cars.

I'm not saying that the oils should be mixed in aviation applications- whatever instructions for the engine/transmission/oil should be followed to avoid bad things.

I'm just curious about the gelling mechanism mentioned. Is this something personally observed?
Click to expand...

In various maintenance manuals as well as operating manuals there are warnings not to intermix turbine oil with petroleum based oil.

I did see a gear box that was disassembled after someone intermixed the oils and ran it. The result was a gooey mess.

Here is a short article I ran across written by a contributor here that explains turbine oil very well.

Turbine oil is synthetic and requires special seals, gaskets and o-rings. The only material compatible with synthetic turbine oil is neoprene. I serious don’t think you will find any for motorcycles.

If you do use synthetic oil it will destroy all of your seal, gaskets, and o-rings and clean the walls of the cylinder so clean it will cause the piston to cease.

There are many requirements for turbine engine lubricating oils, but because of the small number of moving parts and the complete absence of reciprocating motion, the lubrication problems are less complex in the turbine engine than in the reciprocating engine. Because of the absence of reciprocating motion, plus the use of ball and roller bearings, the turbine engine uses a less viscous lubricant. The turboprop engine, while using essentially the same type of oil as the turbojet, must use a higher viscosity oil because of the higher bearing pressures introduced by the highly loaded propeller reduction gearing.

Gas turbine engine oil must have a high viscosity for good load-carrying ability but must also be of sufficiently low viscosity to provide good flow ability. It must also be of low volatility to prevent loss by evaporation at the high altitudes at which the engines operate. In addition, the oil should not foam and should be essentially nondestructive to natural or synthetic rubber seals in the lubricating system. Also, with high-speed antifriction bearings, the formation of carbons or varnishes must be held to a minimum.

The many requirements for lubricating oils are met in the synthetic oils developed specifically for turbine engines. Synthetic oil has two principal advantages over petroleum oil. It has less tendency to deposit lacquer and coke and less tendency to evaporate at high temperature. Its principal disadvantage is that it tends to blister or remove paint wherever it is spilled. Painted surfaces should be wiped clean wìth a petroleum solvent after spillage.

Oil change intervals for turbine engines vary widely from model to model, depending on the severity of the oil temperature conditions imposed by the specific airframe installation and engine configuration. The applicable manufacturer's instructions should be followed.

Synthetic oil for turbine engines usually is supplied in sealed 1-quart or 1-gallon metal cans. Although this type of container was chosen to minimize contamination, it has often been found necessary to filter the oil to remove metal slivers, can sealants, etc., which may occur as a result of opening the can.

Some oil grades for use in turbojet engines may contain oxidation preventives, load-carrying additives, and substances that lower the pour point, in addition to synthetic chemical-base materials.

Sorry for the bad news.
Source(s):

A&P/IA
Aviation Author
http://www.stacheair.com
AC 65-12A

 
If the synthetic oil was ester-based, I could see it breaking down to alcohol and acid and making a gooey mess when the degradation products mixed with the mineral oil (less polar than the syn-oil by itself to keep it all in solution).

For the hypothetical motorcycle cited in the article, Mobile-1 (synthetic oil) and Pennzoil (at one time, mineral oil. I don't know about now with the oil company mergers) could be interchanged amd mixed with little ill effect since Mobile-1, Castrol, etc are built up from olefins into alkanes- essentially the same as the mineral oil, just more controlled.

Simply being a synthetic oil doesn't mean that it couldn't be changed with mineral oil.

It is the type of synthetic oil, and the additives, that prevent a substitution.

Thanks for clearing that up.
 
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