Labnerd, I have a question about synthetic lubricants in jet engines. I don't know what, if anything, you know about it, but maybe you know someone who does.

I had a fellow state to me that the aviation industry has shown with years of research that there is NO BENEFIT using a synthetic oil over a petroleum oil in JET ENGINES. I'd like your opinion on this.

I have read about a couple of military spec manuf. like ARPOLUBE, which does use some petroleum based oils, but I do not know the details.

Anyway, I was wondering if you know of any research that either refutes, or supports the above mentioned statement.

Thanks.

(I would have sent you a PM, but you said you rarely check those).

 

I can't comment on whether there's benefits on synthetic over petroleum. But speaking as an aircraft mechanic for the Marine Corps, I can say that jJet engines in the Marine Corps: including turbojet engines in planes like the f-18, and turboshaft in aircraft such as the ch-53 series helicopters use a synthetic base stock oil in their engines. No petroleum based oils in turbojet/shaft/prop engines in the Marine Corps.

Here's a link to the MIL specs for engine oil used in the CH-53 helicopter.
http://store.mil-standards.com/index...ROD&ProdID=373

 

Is there any flow characteristics or shearing specs greatly needed with high heat, higher RPMs or higher tolerances in aircraft vs automotive apps?

The thing I think would be noticable would be maintenance and filtration in aircraft and the longevity in design with the tolerances in key parts.

 

Well, from everything I've read, the need for even more specialized synthetics has become a necessity with aviation/turbine engine technology. The need for even a greater range of temp stability, etc.

 

jet engines use roller bearings and ball bearings that are spray lubed usually. Automotive engines use a pressure system that use the oil to actually support the parts in a film of oil. They are totally different apps that use different qualities of the lubricant that don't necessarily cross over to the other app. All military uses synthetics. The advantage they have is change interval mostly. There isn't much shear or load on the oil in a jet engine. It has to tolerate high heat from the hot section, and cool the engine.

 

I am a aircraft tech and you can not compare jet to recep. Totally different requirements so you are compareing apples to oranges. I use Mobil 254 and Exxon 2380 both are syn in my aircraft. It is nothing like auto or recep aircraft oil. As per the differance between recp aircraft oil and auto I am not sure. Good luck.

 

Forgive my ignorance, but I do not know what you mean when you refer to an oil as "recep"

 

recep = reciprocating aircraft engines

 

reciprocating= piston engine.. like our trucks... lol

 

Well Doc, jet engines aren't in my field but they are more like your auto transmission than the engine. I am not aware of any dino based oils for jets but there could be a bunch out there- again, not my field. The jet engines oil goes thru many heat cycles that are extreme and the working environment is also extreme. Taking off from a desert airport and climbing to 30,000 ft in a matter of seconds the ambient temp can easily fall 100F. The internals may also be working at temps your engine will never see. Most of the specs I have seen allows little or no coking otherwise bearing failure is guaranteed so I would doubt much in the way of dino oils for jets. I believe that there is also a requirement for antifoaming agents. FWIW, you cannot use oil rated for your engine in any aircraft engine- jet or piston. The formulations are completely different and highly specific.