Lycoming 0-540, Aeroshell 15W-50, 25 hrs.

[wings&wheels]

There aren't too many aircraft UOA's here and I just got the bird's regular 6 mos. oil sample back so here's one if you are interested:

Piper Dakota, Lycoming 0540 (horizontally opposed, air cooled, 540ci, 6 cyl, 235hp), approx 1,600 hrs on the engine (2,000TBO), 20 hrs on the oil and 3 quarts added. Prior sample is from last year w/ approx. 8 hrs on the oil and 1 make-up quart. There were approx 45 hours in between where we didn't get a sample (over zealous apprentice mechanic drained oil before I showed up w/ the bottle ).

6/04 4/03 Avg
Hrs. 20 8 -
Al 3 1 2
Ch 4 2 3
Fe 13 8 11
Cu 2 1 2
Pb 2145 809 1477
Tin 1 3 2
Silicon 5 6 6
Sodium 0 1 1
Calcium 1 0 1
Magnes 5 4 5
Phos 1060 1289 1175
Zinc 2 0 1

Moly, Nickel, Manganese, Silver, Titanium, Potassium & boron, all 0 actual & 0 average.

SUS @ 210F 97.6 s/b 82-105
Flash F 495 s/b >440
Fuel% b Insolubles% b
Lab Comments: "Wear read perfectly at about half average", "all metals in proper balance for engine type", "blow-by characteristics appear normal".

Regards, W&w.

 

[ToyotaNSaturn]

"Pb 2145 809 1477" Is that right?

I've never seen a UOA for an aircraft motor. It's interesting to see the differences between ground and air UOAs.

 

[USAFREOD]

Toyota - most piston engined aircraft run 100LL AvGas, which is actually loaded with lead. The General Aviation community is waiting for a solution, but due to the unique aviation environment (extreme altitude changes) and wide diversity in motors, the UL alternative fuel will only accomodate about 60% of the fleet at the moment, according to EAA.

Wings - AWESOME UOA!!! Wish my O-360 looked that good. Unfortunately, I am over 1900 SMOH, and I am making metal (Fe and Al). BUT... a little birdy told me that Schaeffer's 132 and LC/FP can actually help reduce blow-by and reduce some of the metals in a high-time O-360

and compressions actually improved at last annual...

 

[Jay]

This is an interesting report. Where's the zinc?--or the other detergent and AW/FM adds? I guess aviation oil doesn't have them to help keep the plugs from fouling?

The current crop of certified aircraft engines are so antiquated it's almost unbelievable. Even more unbelievable is their price. Thank you FAA for making general aviation engines unsafe and unaffordable at once.

 

[FowVay]

quote:

---

Originally posted by Jay:
Thank you FAA for making general aviation engines unsafe and unaffordable at once.

---

I think you should thank our lawsuit happy culture and the litigation lawyers for making civil aviation unaffordable today. As for safety, the statistics still show that pilot error is the number one cause of civil aviation accidents. Mechanical failures are very rare.

 

[USAFREOD]

FowVay - it is actually a combination of factors. The cost to test and certify a new design piston engine for aviation is very high, and not due to lawsuits, but to 14 CFR requirements.

The lawsuit costs just add on to the mix...

Just about every part must have a Parts Manufacturing Authority (PMA) approval (like the old MIL-SPEC.) Not every manufacturer, almost every part number... If it is a part that was not in the original design for certification, then you also need a Supplemental Type Certificate (STC). When you install the "new" part, you need to file an FAA Form 337 with the Flight Standards District Office (FSDO).

I installed a new engine monitor that had already been approved for my engine (O-360-A4K), but not my airframe (AA-5B). That minor difference actually require flight testing, an inspection by an FAA Designated Engineering Rep (DER), AND an approved Flight Manual Supplement. This took over 6 months, for a component that already had PMA and TC for my motor!!!

Jay - Aviation oils are "Ashless Dispersant" types, with minimal additive packs (although third parties are starting to market them like AvBlend - which is junk but has "FAA Approval", and ASL CamGuard - which is going through the FAA process and has some Calcium and Zinc compounds I believe...) This is not about fouling plugs (100LL AvGas doesn't need any help!!!) but more about deposit buildup in the valvetrain, which I what I believe doomed AvMobil 1. If Mobil had only done a bit more research...

 

[Jay]

That's interesting. I had heard that aviation engines must use the "ashless dispersant" oils because they can't handle the detergent oils we put in auto engines, but I am not certain exactly why. Maybe the detergent oils are too corrosive? I would think that the detergent oils would be a help with deposit build up and sludge which are big problems in piston aircraft engines.

 

[wings&wheels]

All, I should add that during this sample period, I did a lot of touch and goes & approaches (fullpower, rich mixture, high RPM), probably accounting for the higher than average Pb numbers.

Ashless dispersant oils avoid using metallic additives as aviation engines tend to burn a fair amount of oil and the metallic ashes in the combustion chamber could accumulate, become incandesant and contribute to detonation. At least this is what I'm told and the result of admittedly little personal research. However, I know of a few folks who use car oil in their expermiental aircraft with no apparent problems, one being a Yak with quite a thirst for the stuff.

Wings - AWESOME UOA!!!

USAFREOD, thanks. The Tiger is a nice airplane. Good luck as you get to TBO.

 

[cheetahdriver]

below is my standard, canned reply to this subject that comes up in the grumman gang at least once a year. first time i have put it up here, hopefully molekule will check it for errors.


the reason you do not use automotive oil in aircraft is that the additives in automotive oil are not good for aircraft. Automotive oils use sodium alkylbenzene sulfonate as a detergent additive, and zinc dithiophosphate as an extreme pressure (anti-scuffing) additive. When burned, it leaves ash (zinc oxide). the zinc oxide ash will then plate to the engine head and exhaust valve, causing detonation, since it will not transfer heat as readily as the head itself. depending on your situation, power settings, fuel type (autogas, anyone??)and so on, this will leave you with an extreme cockpit cooling problem once the motor for the fan up front is destroyed.

Aircraft oil does contain a detergent, called by a more technical term, an Ashless Dispersant (AD oil). It is a succinimide. Aeroshell 15W50 also contains triphenyl phosphate as an extreme pressure (EP) anti- scuffing additive. it used to be Tricresyl Phosphate, but they changed when the later was discovered to be a neurotoxin (among other things).

the zinc oxide ash is a metallic ash, almost a metallic ceramic. it doesn't conduct heat very well at all. the ash will stick in a clump to the head, piston or valve (depending on position at ignition front, flow into and out of cylinder, etc). it will then heat up to nearly combustion wavefront temps because it doesn't conduct heat very well. so now you have a glowing piece of stuff attached to your head or piston at about 1700 degrees (well above the 500 degrees that lycoming says is immediate danger for the heads). if it is on the piston, it may correct the problem by burning a hole through the piston (think mini-china syndrome), on the head it will just warp and crack it. in either location you have a dandy glow plug now setting there to ignite the fuel without the formality of the spark plug (preignition), which causes the ignition while the piston is still on the way up on the compression stroke. 10 to 20 times of that and you will be scattering engine components all over the landscape.

aviation oil and automotive racing oils are the only two i know that do not have the zinc dithiophosphate in them. however, as of late automotive racing oils do have a zinc additive in them for another purpose, and this will cause the same problem (some racers are now using aviation oils just because of this). marine and stationary engine oils tend to have alot more of these additives than regular oil. the best oils for an aircraft are aircraft oils. if pricing is an issue, go to your local oil jobber or one of the online oil companies. my personal taste is aeroshell 15W-50 in the winter and 100plus in the summer, am just coming off of exxon elite (ran up my oil consumption (want a case?)).


end canned response.

mobil's AV1 was a very good oil, it was just really expensive. when they tried to extend the OCI on it, was when the lead falling out of suspension bit them in the *** .


scott
owner 79 AA5A HyperCheetah
200HP, constant speed prop

 

[Jay]

Thanks for the explanations, but it doesn't answer why automotive engines (or motorcycle engines, for that matter) have no trouble with sodium alkylbenzene sulfonate or zinc dithiophosphate additives.

 

[veepster]

quote:

---

Originally posted by Jay:
Thanks for the explanations, but it doesn't answer why automotive engines (or motorcycle engines, for that matter) have no trouble with sodium alkylbenzene sulfonate or zinc dithiophosphate additives.

---

Jay,
Reciprocating aircraft engines have a substantially higher oil consumption rate than do their earthbound cousins. Each aircraft engine manufacturer has a specification for "normal" oil consumption. (read x quarts in x hours) This does not go away. (typically)

In W&W's original post, he indicated that he added 3 quarts make-up over 20 hours of operation. Let's say ground vehicles average 30 mph when all kinds of driving are averaged together. (I had an hourmeter in one of my cars for 4 years and it worked out to this)

Okay. 20 hours x 30mph = 600 miles. If any vehicle used 3 quarts of oil in 600 miles it would probably have heavy combustion chamber deposits in addition to other problems. A healthy auto engine typically won't use even one quart in 6,000 miles, let alone 600 miles. Modern auto engines have excellent oil control. If you control oil consumption, you control oil related deposits. Plain and simple.

Aircraft engines operate under high load, low rpm conditions most of the time, especially compared to autos. In a car this would be prime detonation territory, especially if the vehicle has heavy combustion chamber deposits and/or poor quality fuel.

Auto engines don't have problems with the additives because they typically stay where they belong...in the oil system, along with the oil

I'm afraid that I'm oversimplifying a little because auto and aircraft engines differ so vastly just due to their respective operating environments. My attempt was to find some kind of common ground here and oil consumption was all I could think of.

Hope this helps,

veepster

 

[MolaKule]

Cheetadriver;

Very good description.

I would only make one or two minor corrections:

quote:

---

Automotive oils use sodium alkylbenzene sulfonate as a detergent additive, and zinc dithiophosphate as an extreme pressure (anti-scuffing) additive.

---

Automotive oils primarily use calcium sulfonates and magnesium sulfonates (often together) as detergents.

The ashless succinimides (ASMD's) do a pretty good job of both cleaning and dispersing stuff, especially lead sludge. The VII used is most likely a combo VII/Dispersant.

The newer ashless AW adds are primarily Sulfur-Phosphorous (S-P) adds with either TCP or TPP, as TCP is still used in many applications in buffered solutions.

Any additive that contains metal is going going to leave behind those cinders to glow and to cause preignition and detonation in engines (aircraft) that use oil, hence the use of ashless compounds.

 

[cheetahdriver]

wow, did you guys see that, molekule said i had a very good description, with only one or two minor corrections!!!

made my day.

i da man, i da man

hey, when a man like molekule says good things about something i write, it is time to go to vegas, cause it aint goin to get any better than that.

thanks molekule, and i note your changes for my next grumman rant (cause this WILL be coming up again there (and on the piper user group, and the cessna user group)).

 

[Jay]

It does indeed help, thanks.

Sorry for hi-jacking this thread.

 

[benjy]

interesting for sure!! if it has [censored] or tyres or an impeller theres always something to learn!!