The benefits of AD (Ashless Dispersant) oil go a long way.

General Automotive oil, uses oil, which has ash added into it. SAE, and automotive manufacturers claim it is cheaper. But not really...

They want you, as a "misinformed" and "stupid" automotive enthusiasts to put it into your car, not knowing it's true purpose.

Ash oil or your common automotive oil, is used to "not prolong" engine life. In fact, more often than not, it probably shortens engine life.

So here is my basic theory...

Ashless Dispersant Oil, or AD as it is referred to in Aviation, is the "standard" when it comes to reciprocating engines. Why? Well, the main thing is liability.

The FAA dictates that all systems must be redundant, (aka safe a possible). No one certainly wants to see someone fall out of the sky while they are flying their plane, due to mechanical failures.

So, if the FAA mandates reciprocating engines "MUST USE" AD oil, than I say, why in the "HELL"(excuse my somewhat harsh language) are we using it in our cars? Well the answers seem to describe themselves(read my above statements.

Here are some of the main benefits of AD oil:

-1) Possesses a washing action that removes particles, sludge and varnish.

-2) Dispersants keep contaminents from attaching to each other and forming large deposits.

-3)Higher flash point and higher viscosity index number.

-4)Better range of lubricating characteristics.

In theory, this:
Reduces the possibility of:
-Contaminants forming in oil passages.
-Piston Ring grooves from forming deposits.

Automotive oils simply cannot stand up to the loads demanded by aviation, which is a reason why I wonder, if anyone would be willing to experiment with a Renesis by trying it.

The AD oil willl appear more dirty, during the oil changing process(but that is because it's working better).

For you new Rotary enthusiasts, and us old-time folks, or general car enthusiasts we all know that:
Time+wear=engine life.

Carbon deposits within the rotary chamber, more specifically, along the Apex seal grooves and springs are generally what plays a factor(although not a total factor) in effecting Rotary engine and Reciprocating engine life.

The cost, surprisingly, is the same.

More info:
http://www.lanclube.com/Exxon_Elite/...ite_20W50.html

http://www.swaviator.com/html/issueja02/Hangar7802.html

http://www.sacskyranch.com/faq_oil/FAQ00006.htm

Choose your brand:

http://www.sacskyranch.com/faq_oil/FAQ00006.htm

15W50 is about the lightest I can find.

Look at the price simularity:
http://www.sacskyranch.com/acatalog/...Elite_222.html

Just remember however a 20W50 is a thicker oil, the 20 weight oil can operate as low as (0*F) and the 50 as hot as (210*F).

Rotarys run hot, and need great lubrication.

Be forewarned however, I am not by anymeans rich. So if you blow it up, it's your own fault. Simply a discussion of whether it would or would not work.

Just something to think about.


Now, let's discuss

 

You say the ad oil has a higher flash point. You want the injected oil to burn and burn clean in a rotary. That is why 2-stroke ashless formulations would work best for injecting in the motor.

 

Yes, an engine lubricating oil should have a high flash point, so that the vapors it gives off can withstand the high temperatures encountered within the engine.

 

One more thing to add:

During break-in it would probably be best to start with striahgt mineral oil.

It aids in quicker seating of the seals.

After you're finished with engine break-in, then go to AD oil.

 

The properties of petroleum-based oils

Dispersant

Dispersant action is the property of an oil that prevents the sticking together of carbon-based particles thereby keeping them in suspension. This characteristic inhibits the settling and depositing of carbon on engine parts and prevents sludge from clogging oil passages. Sludge is a mixture of oil, carbon, water and byproducts of combustion.

Ash

Automotive engine oils contain metallo-organic compounds of calcium, magnesium and zinc that serve as detergents and anti-wear additives. When exposed to the high temperatures in a combustion chamber, these additives burn and form a metallic ash deposit on spark plugs and exhaust valve stems. If used in aircraft engines with their relatively high oil consumption, these ash deposits would tend to foul spark plugs and prevent exhaust valves from closing. Ashless aircraft oils use more expensive non-metallic additives to perform the same function.

Viscosity

Viscosity is the oil's resistance to flow or its "thickness". The viscosity used depends on engine design and ambient operating temperature. 80 and 100 grade oils are normally used at low to medium ambient temperatures while 120 grade is used at high temperatures. Most radial engines use 120 grade.

http://www.wearcheck.co.za/sharedhtml/flyerissue3.htm

 

This seemed to me to be a telling point from www.swavaitor.com

"7. Automotive oil should never be used in an airplane engine.
The most important reason not to use automotive oil in an aircraft engine is the number of additives in it that are designed for use in water-cooled engines operating within a certain range of temperatures and pressures and at constantly changing levels of power. Aircraft engines are air-cooled and operate under an entirely different set of parameters. "


Would not the converse be true, i.e.,

"Airplane oil should never be used in an automobile engine."

for the same reason mentioned above?

 

Huh? what do you mean by vapors have to "withstand high temperatures.."?

 

the air-fuel ratios are dropping down to around 12-1 starting somewhere abov 6k, dont remember exactly where though
________
FREE XXX AMATEUR

 

I would like some more thoughts on AD oil...some of the additives in put in dino oil only benefit piston engines...lets revive this discussion

 

Does this type of oil have something to do with planes in WWII? Was this type of oil used in the superchargers of these planes? I rememer hearing something about this, correct me if I'm wrong...

FS

 

Iknow this thread is seriously back from the dead but anyone? RG for instance

 

I was under the impression that aviation oils are not based on hydrocarbons but on esters... Would not freeze, be of better quality (i.e., viscosity index), stable at higher temps (no deposits), etc.
Now, the old rotary engines were avoiding the synthetic oils because of seal issues... but the actual damaging chemical from synthetic oils was the ester used in small amounts to promote solubility of other oil additives in the synthetic base stock.
So I would be very scared to put a full aviation oil in a rotary engine. I would better use a higher vis oil grade (5W-40).... but for now I stick with the dealer oil changes. I do use premix - high RPM motorcycle 2-cycle oil, 1/600 dilution in gasoline.
Just my $0.02

 

I have been really diggin deep into aviation fuel and oil. I currently work as a Airport Manager so I easy access to them. Being a Rotary guy for over a decade, Ive been interested in the results running the 100LL fuel and AD oil in my RX8.

Theres already a thread on 100LL, i will post my results in that thread on the great attributes AV Gas has, and why you want to use it in a Rotary engine.

On to the oil, Ashless Dispersant Oil- After using AV Gas, I wanted to look into the oil that Aircraft are using. The fuel is way better and proved to be a great option for a Rotary, so how about the oil. I began looking at Aircraft that actually use the Rotary engine. there are many 2nd Gen 13b's and i found a Ren too. They use Aviation fuel and oil.

One thing thats pointed out is that Aircraft engines are Air Cooled versus automotive engines are water cooled( with the exception of the VW Bug)
And the Oil in the automotive industry has been changed so much over the years with so many different additives to support it.

Aviation oil hasnt changed so much, the only thing I have found is that they have a additive that helps against engine corrosion, as many aircraft to sit alot and for long periods of time versus driving your car everyday.

Check this Article out from- https://www.avweb.com/news/maint/oil..._197096-1.html

Why shouldn't I use automotive oil in my airplane to take advantage of the more advanced technology?

While it is true that automotive oil is far more advanced than aviation oil, the answer lies in the fact that most aircraft engines are air-cooled while automotive engines are water-cooled. Air-cooled aircraft engines are built with greater clearances and are designed to consume (burn) some oil. Water-cooled automotive engines are designed and built to much tighter tolerances, so they do not consume much oil. These differences in design tolerances are due to the large temperature differentials that are found in high-continuous-power-output, air-cooled, aircraft engines versus the low- and intermittent-power-output, water-cooled, auto engines. There can be a 300 degree F temperature difference between the cylinder head and cylinder base in an operating aircraft engine. That kind of temperature differential causes a lot of distortion in the cylinder, necessitating the requirement for large clearances. Automotive engines, being water-cooled, have lower temperature differentials across the engine and thus suffer lower levels of distortion and can be designed and built to tighter tolerances. Aircraft engines were designed before additives were available and have not really changed much over the years. When ashless dispersant oils were introduced for auto engines, they were also suitable for aircraft engines and eventually were adopted for aviation use. However, when zinc antiwear and metallic detergents were formulated into auto oils, an important divergence occurred. Aircraft engines burn a fair amount of oil and, if these metal-containing detergents and antiwear compounds are present, they can form metallic ash deposits in the combustion chambers. These deposits can lead to destructive preignition, which could burn holes in the tops of pistons with obvious catastrophic results. For that reason, it was decided that aviation oils were to remain ashless to avoid the risk of metallic deposits. The benefit of using ashless dispersant oils is, obviously, a cleaner engine. Aircraft engines would also benefit greatly from the addition of other automotive additives such as anti-wear, detergents, and corrosion inhibitors, but the downside is added cost. Ashless versions of these performance additives can cost up to 10 times more than standard ash-containing additives.
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*NOTES*
Air-cooled aircraft engines are built with greater clearances and are designed to consume (burn) some oil..........Rotary burns/consumes oil and has greater clearances with Apex Seals and oil rings.

States that aircraft engines are high-continuous-power-output //// so continously high RPMS causeing different temperatures between heads n blocks n such versus a watercooled auto engine- as we know, one of the design flaws of the Rotary engine is the combustion side of the rotor housing being exposed to constant heat with no breaks of cool down versus a 4 cycle auto engine having times in between its cycle to have cool downs.

Aircraft engines burn a fair amount of oil and, if these metal-containing detergents and antiwear compounds are present, they can form metallic ash deposits in the combustion chambers. These deposits can lead to destructive preignition, which could burn holes in the tops of pistons with obvious catastrophic results.--------------Rotarys burn fair amount of oil and we have a huge issue with carbon deposits and burn thru apex seals and oil seals- So using a oil that do not have these detergents and such is a must!

The benefit of using ashless dispersant oils is, obviously, a cleaner engine.---This what we want for our Rotarys to live a long and fruitful live!

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More of the Article

This is a common and emotionally charged question. Let me start with a description of multi-weight oils. Multi-weight oils are simply those oils that contain a viscosity modifier (VM) that affects the viscosity profile of the oil with temperature. To produce 20W-50 oil, you start with straight 20-weight oil and dissolve approximately two percent of a solid polymer (the VM) into it. The VM does not affect the low temperature viscosity of the oil because, when cold, these polymer molecules ball up so tight and small they, in effect, disappear in the oil. As the oil warms, the VM molecules relax and interact with each other. This interaction impedes flow, which by definition is an increase in viscosity. This essentially means that at 0 degrees C (32 degrees F), the 20W-50 flows like a 20-weight oil and at 100 degrees C (212 degrees F), it has the same viscosity and flows like a 50-weight oil. In effect, the viscosity modifier reduces the oil's tendency to thin with increasing temperature. All this being said, how does this affect the oil's ability to protect parts from corrosion? The two properties that are important for corrosion resistance are film thickness and additive activity or concentration. At ASL, we performed a simple experiment to compare the inherent corrosion protection of straight 50-weight versus 20W-50 multi-weight oil. The two oils selected are popular products and neither contained any ferrous-metal rust inhibitors. Test panels were weighed, then dipped in the two oils heated to 100 C (212 F). They were placed in an oven, which was 100 degrees C (212 degrees F), for 30 minutes. The panels were allowed to cool and film thickness was determined by weight increase. This procedure simulates the oil-film thickness found on cams, lifters and other components in an engine after shutdown and cooling. It was calculated that the film thickness was under a thousandth of an inch, 0.0008 inches, for both samples. The fact that we measured the same film thickness is not surprising, as both oils are designed to have the same viscosity at the elevated temperature. When tested for rust protection in a standard, humidity-cabinet test, both samples failed in much less than 24 hours. This test demonstrates that oil film alone, in the thickness range that these oils leave on engine parts, offers very little rust protection.



The article continues to talk about a additive called CamGaurd to help against oxidation--- I skipped this because using the AD oil in our vehicles the car wouldnt be sitting for long periods of time and shouldnt be worried about the oxidation.... But you should be aware that AD oil doesnt have any additives in it for rust unlike automotive oils.



After reading this, I am leaning toward using AD oil in my RX8. but what weights are there?
For me I think running AD oil during the summer and maybe just for track days.
This it what I have gathered and what I have taken from it. Solely my opinion. Im not a scientist or even that smart, so take what ive said with a grain of salt

 

We've changed API specifications about 4 times since this thread was started. There are plenty of detergent packages in modern oil that keep things clean for automotive purposes (where oil can circulate, obviously, so not the rotor seals). RX8 engines don't usually die of bearing failure or any other oil-related issue anyway.

The common mode of failure has a lot more to do with long term wear and carbon deposition from fuel. Engine oil can't help you there. Injecting and premixing ashless 2-stroke oil has a better chance, but we don't exactly have hard research data on that.

Also don't run 100LL if you have a cat. You will destroy it quickly.

 

Hmm some good knowledge here,

lol as for a CAT....whats that lol... first thing to go on any rotary car.