Jet turbine engine oils

[Tom NJ]

Hi Johnny,

Chances are any lubricant or hydraulic fluid you are using has some additives, but the type and amount may vary. The 83282 is about 70/30 PAO/diester and contains 2-3% additives. The 7808 is 96% POE and has 4% additives. Most of the additives in the 83282 and 7808 are different, but they both contain 1-2% of a phosphate additive. This phosphate is not known for causing skin problems to my knowledge, but you may be very sensitive to something in these oils. Best to avoid contact.

Tom

 

[Tom NJ]

Oops - meant to say "Hi Oil Pan". Sorry Johnny.

 

[oil pan 4]

Hey thanks.
That is what the warning on the 55 gallon drum is for, the phosphates. I didn't know that 83282 had diester in it. I guess some thing has to thicken it up. It is thicker compaired to the straight PAO.
One thing I have seen 83282 do is melt pavement into mush must be the diester.
It is safe to say cause of this site and every on one on here I know way more about the stuff in the 55 gallon durms at work then any one else.

 

[Tom NJ]

Hi Oil Pan,

The diester in the 83282 is actually slightly thinner than the PAO and is there to help the seals. PAO tends to shrink and harden seals, while esters tend to swell and soften seals. A little swelling and softening is better than shrinking and hardening, so the oil contains 30% diester to counter the effect of the PAO.

Diesters won't melt pavement. They may clean it a bit but otherwise should be neutral, unless your pavement has some kind of incompatible coating or binder. Even then 30% in a PAO should not cause any harm. Our factory is paved and we have been making esters for over 55 years and never noticed such an effect.

Tom

 

[JAG]

Tom, you should get the Poster of the Year award, if there was such a thing. Many thanks for all the knowledge you've shared in this thread and many others.

 

[Tom NJ]

Hi JAG,

Thanks! Nice to know that all this useless knowledge accumulated over the years is doing some one some good.

 

[tom slick]

Thanks for all the info, I soaked myself in 7808 and 23699 for 10 years in the USAF.
Do you happen to know why C-130E/H aircraft with allison T-56 engines use any 23699 but the C-130J with a RR AE-2100 uses Mobil Jet Oil II exclusively?
I know it's a specific question but nobody else can give me a decent answer, including the RR rep.

 

[Tom NJ]

Hi Tom Slick,

Rolls Royce insists on approving oils based on their own testing, and then by brand name. That said, the US Military insists that all of their engines must operate on any 23699, so I'm not sure why MJ II is called out for this engine. I'll call the military approving authority at NAVAIR and see what I can learn.

Tom

 

[tom slick]

Does NAVAIR dictate/specify for USAF birds? especially USAF only birds? USN and USMC doesn't fly the J model.

 

[Tom NJ]

Hi Tom Slick,

The oil use responsibilities are split by the oil type rather than the aircraft type. NAVAIR at Patuxent River controls everything to do with the 23699 specification, including specification revisions, the qualified products list, and use & maintenance practices. AIR Force Research Propulsion at WPAFB conrols the same things for the 7808 spec. NAVAIR should, in theory, know why a specific brand of a 23699 is called out for a specific aircraft. We'll see

.

Tom

 

[TooSlick]

Tom NJ,

Much thanks for the excellent post on jet turbine oils...something I've been interested in for some time.

Of course we should point out to the "Newbies" that jet turbine oils aren't exposed to the byproducts of combustion. The main design criteria is excellent, extreme temp viscometric performance and thermal/oxidative stability.

There is VERY little correlation between this application and an internal combustion engine.

thanks again for the informative post....

Ted

 

[Tom NJ]

Hi Ted,

You are absolutely right - one cannot use jet turbine oils in an internal combustion engine! Turbines have no blow-by and virtually no highly loaded areas. The turbine oils are very thin, have no detergents or dispersants, and act more like a coolant than a lubricant.

Tom

 

[tom slick]

Thanks again Tom, great info.

 

[24 VALVE]

Hi Tom, thanks for your time posting all this interesting information on a facinating subject (to some of us anyway).
But please answer this question. In the unloaded turbine engine, say a typical huge jet engine, the amount of fuel going through it being thousands of gallons on a coast to coast flight (or further), how does the oil serving the bearings on each side of the hot section keep from getting
any combustion particles in it?

Is the seal that good to where almost zero combustion by-products cannot enter that oil?

Great stuff! Thanks again.

 

[Tom NJ]

Hi Tom Slick,

I spoke to the 23699 authority at the Navy about your question on the C-130J oil recomendation for MJ II. There is a trend in the military towards "power by the hour", that is, instead of buying the jet engines, the engine builders provide the engines and the military pays for the use of the engine by the hour. The military is buying the power, not the engine, in the same way you pay for electricity but don't buy the generator.

As part of these arrangements, the engine builder must guarantee a specific amount of hours for the engine, and therefore has a say in the maintenance practices. As I mentioned before, Rolls Royce approves oils by brand rather than by spec, so for their engines at the military under this scheme they require the use of their approved oils only. They only have five oils approved for this engine, which includes Mobil Jet II but excludes the 23699 C/I oil used extensively by the Navy and other branches. Therefore the military buys MJ II for this engine.

This "power by the hour" trend is relatively new and only affects a couple of engines so far. Not everyone in the military welcomes the move, especially those in logistics. The military has a hard enough time purchasing, stocking, and distributing two oils today (they keep running out!) - imagine the problems if they are expected to become a drug store having different oils for different engines around the world. There is some opposition to this trend which will need to be ironed out in the coming years. In the mean time, the C-130J is an exception engine using MJ II oil.

Tom

 

[Tom NJ]

Hi 24 Valve,

Yes the seals are very effective at preventing blow-by contamination of the oil. The oils do not go black and the OCI for commercial jet engines is about 20,000 to 30,000 hours or 6-10 years. As mentioned before, however, frequent top-off turns the oil over in the engine regularly.

Tom

 

[tom slick]

WOW! very interesting! the entire J model is a strange deal.

24 valve,
on the engines I worked on it actually had airflow going out of the seal so that nothing could come in. it was a knife edge/honeycomb arrangement at the interface between the high pressure turbine and low pressure turbine (refered to as #4 bearing area). all of the other bearing/sealing areas are completely sealed and do not come into direct contact with the gas path like a recip engine does in it's piston ring area. it also doesn't have the gas pressures that a recip engines see. I worked overhaul on the GE F-110 series, the core is very similar to many GE commercial and military engines.
I could go on...

 

[24 VALVE]

Thanks Tom NJ and tom slick!
Wow, 20,000 to 30,000 hours.....roughly the equivalent to
a million plus miles on an IC engine.
It makes sense to use bleed off air to pressurize the bearings, there is so much of it available on a turbine
engine. Amazing pieces of machinery!

 

[Quickbeam]

Tom, my partners and I operate a L-39C with the Ivchenko AI-25-TL engine. We're using Royco 481 which is Mil PRF-6081. Do you know anything about this oil and are you aware of a readily availible substitube in the US? Thanks.

 

[Tom NJ]

Hi Quickbeam,

The Royco brand name was originally from Royal Lubricants in New Jersey (NOT to be confused with Royal Purple). Royal was a Shell company specializing in aviation lubricants, mostly synthetic, and was purchased by Kaufman Holdings in 1996. Kaufman Holdings also bought Anderol, a company specializing in synthetic industrial lubricants, and combined Royal and Anderol. The company is now under the Anderol name with the Royco brand continuing as a product line.

Kaufman Holdings also owns Hatco, making Anderol a sister company, therefore "the Royco 481 is the world's greatest oil ever!!!"

Seriously, I don't know enough about the available 6081 oils to make comparisons, but I can say that the Royco products are well made and have a long (50+ year) history and excellent reputation.

Tom