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Best Gear Oil?

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TXFlyGuy

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After learning of two incidents of prop governor failure due to contamination from the PSRU, what is the best gear lube?

On AutoPSRU.com, they strongly recommend 85-140 mineral oil (GL-5) saying this is the only proven oil to run quiet, smooth and cool, without foaming issues.

All of the Autoflight New Zealand PSRU's (Titan Mustangs) run Valvoline 75-90 Syn Oil. And the manufacturer says this is suitable.

I noticed some foaming in my oil lines, and my gearbox has a noticeable high pitched "whine". Enough that it got my attention. And I have the 75-90 Syn Oil in my gearbox.
 

delta

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There seems to be a vast selection of filters designed for gear oil. I'd do a little research and get one that would work for you.
 

TXFlyGuy

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Just got off the phone with Stuart, of AUTO PSRU's. He says that after much research, and consulting with various oil companies, they now recommend AMSOIL 75-110 Severe Gear Oil.
 

TFF

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I would only type and brand that the manufacturer says to.

The brand helicopters I work on want Mobile 1 syn 75-90. The gearboxes were designed before synthetic in the 60s. Some parts of the world, Mobile 1 is not available so in those parts they have come up with alternates. This is a certified aircraft.
 

TFF

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These gearboxes were designed for airboats correct? What about attitude? Airboats go through gyrations for sure, but they sit flat most of the time. Your plane being a taildragger sits nose up on the ground. Is it sitting on the ground where it’s not picking up only oil? Sucking some air. If that is not the case, the system probably needs a slobber pot to separate the air and oil. If in the end you are on your own from the factory, use what the survivors use.
 

TXFlyGuy

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These gearboxes were designed for airboats correct? What about attitude? Airboats go through gyrations for sure, but they sit flat most of the time. Your plane being a taildragger sits nose up on the ground. Is it sitting on the ground where it’s not picking up only oil? Sucking some air. If that is not the case, the system probably needs a slobber pot to separate the air and oil. If in the end you are on your own from the factory, use what the survivors use.
No. Autoflight builds gearboxes for aircraft, including gyro-copters and T-51 Mustangs. Not sure, but they might build these for race bikes too.
 

TFF

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Still go back to basics. If the engine is running, at least one quart of oil is on the gear train lubricating. With that quart now not at the bottom of the sump, is there plenty of oil at the pickup point? If the answer is yes, you need an air oil separator; every aerobatic plane, fighter, NASCAR, Indy car, F1 car has one. You can mask it with different oil if lucky.
 

Hot Wings

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I would only type and brand that the manufacturer says to.
Ditto.

As one that has had to go through this many years ago with resonance on a Fiat 128 gear box - viscosity can/does have an effect on resonance.
 

TXFlyGuy

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Ditto.

As one that has had to go through this many years ago with resonance on a Fiat 128 gear box - viscosity can/does have an effect on resonance.
And that is why I will try the Amsoil 75-110 during taxi tests. My gearbox has a loud, high pitched whine. I'm told they all do, but I have never heard this before. This is the very first HD Gearbox. Never tested before.
 

TXFlyGuy

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Following is my post on the Titan Forum:

This is my experience, yours may vary...

I have the new Heavy Duty PSRU. It's the first one produced. The gears are substantial, rated for 600 hp. We are now doing engine runs, and short taxi tests. Checking the prop and governor for responsiveness.

There was some foam noticed in my oil line, not a good sign. For the record, Valvoline 75-90 Synthetic is the oil in the gearbox.

The other item that got my attention...my gearbox has a very noticeable high pitched "whine" sound. This has never been heard before on any other T-51. At least, not as loud and whining as it is on my PSRU. And I have listened to many T-51's running, on the ground and inflight. Many videos have been recorded also. I went back and listened to these, and did not detect the same high pitched whine that my gearbox has.

The manufacturer was contacted. The question was asked..."Is this whining sound normal?"

The response..."What is normal? I have never heard any of my gearboxes run."

With the recent problems with China Doll and Lady Elaine, some investigation was undertaken.

After doing many online searches for info on gear oils, I found a lab report that was very exhaustive and thorough.

http://www.syntheticwarehouse.com/br...lube_study.pdf

Yes, it appears these folks are Amsoil dealers, but that does not diminish the findings of the lab's analysis and rankings. Note that Valvoline failed several tests (as did several oils), especially the foaming test.

A phone call was placed to AUTO PSRU's, and I spoke with Stuart, the owner of the company. He stated that they did a thorough research on the matter, contacting all of the major oil companies seeking the best solution. Amsoil recommended their 75W110 Severe Gear Oil, specifically for aircraft gearbox usage. So that is what they run in all of their PSRU's, and that's what they recommend their customers use.

Based on all of the above, the Valvoline oil in my PSRU will be drained this week, and replaced with Amsoil 75W110.

You are all grown adults and can make up your own mind as to the best course of action that suits you. I know what I'm doing, and the reasons why are stated here in public.

Valvoline is one of the less expensive oils. Amsoil is one of the most expensive. When you own and fly an airplane that costs $150,000, $200,000, or more, a few dollars extra per quart is not even a consideration.
 

TXFlyGuy

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Yes, and the oil will be changed at 5 hour intervals through 20 hours, then 10 hour intervals up through 50 hours. Then every 50 hours.

Am I the only one who was shocked to hear the manufacturer's response, stating he has never heard his PSRU's being run, so he has no idea what sounds they emit?
 

GTX_Engines

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Very interesting stuff. We don't get into the higher HP stuff, but our Yamaha conversions are still pushing the gearboxes we typically use.

Whine is something I've noticed in a number of new builds (sounds like a super charger) but it always goes away after break in. So in our case it is just the gears seating together.

I always get asked about what gear oil I recommend. I'm going to try this Amsoil 75W110 and pass the word along.
 

GTX_Engines

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Yes, and the oil will be changed at 5 hour intervals through 20 hours, then 10 hour intervals up through 50 hours. Then every 50 hours.

Am I the only one who was shocked to hear the manufacturer's response, stating he has never heard his PSRU's being run, so he has no idea what sounds they emit?
He builds the gearboxes, you build the aircraft. How many different applications and engine-gearbox combos can you imagine for the use of a rather generic gearbox, that might have nothing new but the housing to attach to a particular motor you want to run it on? Not possible for the gearbox guy to have experience with every different type of installation. It's best for the two of you to work together to come up with a reliable combination.

I'm not sure who you are working with, but I've known Neil Hintz from AutoFlight to travel from down under to Florida to check out his prototype work on a new gearbox adapter he built for Ernie Boyette on a Yamaha YG4 back in 2011. That's an expensive trip.
 

TXFlyGuy

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Very interesting stuff. We don't get into the higher HP stuff, but our Yamaha conversions are still pushing the gearboxes we typically use.

Whine is something I've noticed in a number of new builds (sounds like a super charger) but it always goes away after break in. So in our case it is just the gears seating together.

I always get asked about what gear oil I recommend. I'm going to try this Amsoil 75W110 and pass the word along.
Ok...good to know. Perhaps the high pitched whine will abate after break in, I hope so. Yes, that is a good description sounding very much like a super-charger.

A good friend thinks the whine associated with my PSRU is due to the much larger and heavier gears, and perhaps the angle of the gear teeth.

Not sure what you consider high horsepower, but we will have 412 hp on tap at 4500 rpm. That's max continuous for the PSRU. Normal cruise will be 3200-3400 when just "loafing around".

If I'm in a hurry, 4150 rpm will be the power setting. Hoping to see some impressive speed numbers! That rpm keeps the prop tips right in the "sweet spot" of about .65 Mach.
 
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rv7charlie

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Helical cut, or spur gears? Did they go from helical to spur with the upgraded gearbox? (Spur is typically noisier.)

I hope that something was lost in translation from the Aussie.... I'd be pretty uncomfortable with spending that much money on something the designer/builder had never even heard, much less flown himself.

Just out of curiosity, how are you *seeing* foaming in your oil lines? The only answer I can think of makes me *really* uncomfortable. :-0

Charlie
 

TXFlyGuy

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Helical cut, or spur gears? Did they go from helical to spur with the upgraded gearbox? (Spur is typically noisier.)

I hope that something was lost in translation from the Aussie.... I'd be pretty uncomfortable with spending that much money on something the designer/builder had never even heard, much less flown himself.

Just out of curiosity, how are you *seeing* foaming in your oil lines? The only answer I can think of makes me *really* uncomfortable. :-0

Charlie
Not sure about the gears, but as they are bigger / heavier, and depending on the angles, that may induce the whine that sounds exactly like a super charger.

I can see the foam in the oil line, which is a blue clear line on the left hand side.
P1050786.JPG
 
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