Synthetic Oil

Chris, I meant an oil filter. The only way to take away the dirt out of the filter-less enginge is to change the oil.

Woofa Express, maybe a misunderstanding? Also aviation engine oil is slightly alloyed. Old Lycoming etc. may not use heavily alloyed HD oil due to combustion residues. But even a lightly alloyed engine oil gets dark in 100 ml.

I worked in the oil industry. If you tell me the exact oil name you've filled in, I can probably say more.
 
Werner said:
Chris, I meant an oil filter. The only way to take away the dirt out of the filter-less enginge is to change the oil.

Woofa Express, maybe a misunderstanding? Also aviation engine oil is slightly alloyed. Old Lycoming etc. may not use heavily alloyed HD oil due to combustion residues. But even a lightly alloyed engine oil gets dark in 100 ml.

I worked in the oil industry. If you tell me the exact oil name you've filled in, I can probably say more.
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Yes Werner, I'd like to have your comments, however let me write, tomorrow, and I'll give you my thoughts and reasons and more details on oil types. cheers, gary
 
woofa.express said:
Yes Werner, I'd like to have your comments, however let me write, tomorrow, and I'll give you my thoughts and reasons and more details on oil types. cheers, gary
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Rotor wrench had some pertinent comments on the use of Synthetic oils also.


Further to mycomments on Synthetic oil.

Following my input on synthetic oil I received a difference of opinion from my friend Mark and an enquiry from Werner, so please let me elaborate on my experience and reasoning.
The engine I had my experience on was a Continental IO520 in my Beech Bonanza. The I means injected and the O is normally aspirated, the 520 is the engine cubic capacity of the engine in cubic inches.
In all piston aeroplanes one has control on the fuel mixture for as one ascends the air becomes less dense thus the fuel needs to be leaned. It is recommended practice to run the mixture so as the exhaust gas temperature is 50 degrees F rich of peak temperature. Thus plugs and pistons will carbon over time. In past years avgas contained tetraethyl lead, and I think the same in motor spirit also. This created a build up of this lead in the cavity of the plugs and needed cleaning regularly. These days many pilots run 50 degrees lean of peak exhaust gas temperature and many have damaged their engines to the extent they need rebuilding. The reason being they should reduce power to accommodate this practice and they aren’t doing so. There are two traditional types of oil for these engines. 1, normal mineral oil which is recommended for newly overhauled engines, it has better lubricating properties, and 2, detergent oil which scavenges carbon. I found the synthetic oil was not scavenging the carbon so I returned to detergent oil and it was black in an abnormally short period. I continued to change at short intervals until normality returned. I might add there is one way to clean all the carbon out of these engines. Fill the fuel tanks with Jet fuel (kero) and they become instantly clean, however the engines fail on or shortly after takeoff.
On radial engines it is common practice to keep the mixture lean on the low altitudes where I am accustomed to operating however I did lean off a little. I’d take the aeroplane for a flight at night and see big blueflame which is unburned fuel. I’d lean off until the blue diminished but remained blue. I’d make a note or mark on the throttle quadrant and lean the mixture after takeoff to that position. On oil burn, I once bought 18x44gals of oil then took a Penzoil agency and lost it when I was told I didn’t purchase sufficient for an agency. I had purchased 72X44gals. The burn was about 1 gal per hour on a newly rebuilt engine which when settled in about 3 gals a day.
On gas turbine engines (jet) the mixture is controlled by a fuel control unit. This requires no pilot input. I thought it was Christmas when I purchased my turbine Airtractor. Easy engine management plus pilot comfort knowing engine failure was most unlikely. (Did you realise the big fan up front keeps the pilot cool, for when it stops the pilot gets very sweaty very quickly).Turbines use synthetic oil, it doesn’t get black and the reason is because it doesn’t get exposure to the fire place.The burn is less than 1 quart for a days work.
Maybe I should try synthetic oil in my town car but I would need convincing it has an advantage in a not so close tolerance built Model A engine.We are told so many lies by governments and commercial product manufactures I have become a sceptical person.
Are you sceptical? Do you believe all you are told?
 

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rotorwrench said:
There are distinct differences between air cooled aircraft engines and any other type. Most have large bores compared to automotive engines to give them the displacement that will develop horsepower in the range needed. Many are still carbureted and the rest are mechanically fuel injected. There are few with channel chrome plated cylinders now days but there may be a few still running. They run in the neighborhood of 215 degrees F and more depending on conditions. These are extremes for piston engines. It takes a strong detergent quality to scavenge the combustion bi-products that get past the rings. It also takes a minimum of SAE 50 viscosity index to do a decent job of lubricating. Mineral based ashless dispersant scavenging additive can easily be blended in and still hold the viscosity pretty well at 100 degrees C since there is a wide band of viscosity index available in mineral based lubricant stocks. Ester based synthetics are a different story. The are strictly a low viscosity lubricant that has to have viscosity building polymers blended in to give it the SAE 50 viscosity. These polymers break down quickly at high temperatures. This is why many of the synthetic aviation motor oils are semi-synthetic which is a blend of mineral and synthetic based stocks. Ashless Dispersants work better in mineral based oil than they do in synthetic so this is another reason for the mix. Aircraft that fly up in the colder atmosphere can get away with using semi-synthetics but helicopters and smaller aircraft usually stay in the lower altitude ranges. Take off for airplanes is usually full power until a cruise altitude is reached and helicopters run at high power settings anytime they are hovering or gaining altitude so they get wrung out pretty well in normal operations.

I learned a long time ago not to use synthetics in the helicopters. They would never last on the stuff. Aeroshell W100 or W100+ are the most common used. The plus has TCP as an additive for Lycoming engine cam follower well being but can not be used in engines with integral clutches or overrunning clutches since they might slip with that oil. Straight mineral is only used for break in.

Automotive engines have no real comparison to aircraft engines other than they are a reciprocating piston design.
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I endorse what rotorwrench has written.
 
Hallo Gary, the Continetal engine is known to me, it is also flown in Germany. But aircooled aircraft engines that run on AVGAS (leaded gasoline) and generally operate at a fairly constant speed can not be compared to car engines. This changes the requirements for the lubricating oil. But that's another topic.

In principle, unalloyed automotive engine oils remain light because they do not dissolve the soot that forms during combustion. The dirt settles inside and is only partially discharged during the oil change. Oils with cleaning additives (HD) dissolve soot in the oil, and when replaced, the dirt protection is rinsed out.

Synthetic oils tend to be somewhat aggressive on their own, thereby dissolving soot and keeping it in suspension. Synthetic oils are additivated differently, the main danger here is the corrosion.

As a rule of thumb, thick mineral oils leave more residue in the combustion chamber than low-viscosity mineral oils. Modern synthetic oils burn almost without residue and also clean the engine interior.
 
Synthetic oils were found to be excellent for turbine type engines due to their very high flash point (the point where they will actually combust). Turbines operate at extremes that would cause mineral based oils to vaporize and this could lead to combustion. Synthetics vaporize at a higher temperature and they don't combust as easily.

The advent of viscosity building polymer plastics is what allowed the synthetics to be used in a much wider variety of applications. Eventually the synthetics may be the only thing going for automotive use. There is still mineral base oil around now but it's hard to say how much longer it will be available. It's already getting harder to find certain mineral based lubricants due to low demand. I'll keep using it as long as I can anyway.
 
rotorwrench said:
Synthetic oils were found to be excellent for turbine type engines due to their very high flash point (the point where they will actually combust). Turbines operate at extremes that would cause mineral based oils to vaporize and this could lead to combustion. Synthetics vaporize at a higher temperature and they don't combust as easily.

The advent of viscosity building polymer plastics is what allowed the synthetics to be used in a much wider variety of applications. Eventually the synthetics may be the only thing going for automotive use. There is still mineral base oil around now but it's hard to say how much longer it will be available. It's already getting harder to find certain mineral based lubricants due to low demand. I'll keep using it as long as I can anyway.
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I have frequently used diesel in turbines when jet wasn't available. In Malaysia it was entirely diesel and boy the exhaust fumes burned my eyes when climbing in or out of the aeroplane. It has a higher specific gravity to Jet, 0.80 compared to 0.75 for jet with variations depending on whether it is winter or summer blended. Jet can be turned to diesel by adding oil. If diesel is used in winter here in Australia, the engine needs to be started in the morning with jet otherwise we get what is a hung start. Diesel has a higher sulphur content and is more corrosive on the power blades. Diesel has more energy than Jet, I see this on the fuel flow when I open the throttle. My town car is diesel and I try to avoid the higher performance diesel when I gas up because it is made by adding lights such as kero. The cheaper fuel (no additives) has more than sufficient performance and provides a slightly better range, or more energy or work in a tank full.
Oh I have not made the point I have in mind. A turbine will, I'm told, burn lubricating engine oil as fuel and thus the comment from Rotorwrench above.
 
Werner said:
Hallo Gary, the Continetal engine is known to me, it is also flown in Germany. But aircooled aircraft engines that run on AVGAS (leaded gasoline) and generally operate at a fairly constant speed can not be compared to car engines. This changes the requirements for the lubricating oil. But that's another topic.

In principle, unalloyed automotive engine oils remain light because they do not dissolve the soot that forms during combustion. The dirt settles inside and is only partially discharged during the oil change. Oils with cleaning additives (HD) dissolve soot in the oil, and when replaced, the dirt protection is rinsed out.

Synthetic oils tend to be somewhat aggressive on their own, thereby dissolving soot and keeping it in suspension. Synthetic oils are additivated differently, the main danger here is the corrosion.

As a rule of thumb, thick mineral oils leave more residue in the combustion chamber than low-viscosity mineral oils. Modern synthetic oils burn almost without residue and also clean the engine interior.
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hello Werner. thanks for that. would you please clarify and perhaps expand on the corrosion aspect. with thanks, gary
 
I think we come too far from the original topic "car engine oil"?

In short: Poly(ethylene)glycols form aggressive acids during combustion. Therefore, such oils are more additized to corrosion protection. An alkaline additive is added. That neutralizes. It consumes itself in constant circulation. Measured to control the basic buffer, TBN (Toatal Base Number).

The critical stress (wetting ability), i. e. cylinder bore, is worse with PEG and must be compensated again by additive. Etc.

The current trend goes towards synthetic esters. They already have very good properties as the base oil component and require little additives and burn almost without residue. They are very temperature stable.

In a layman's terms one could explain "synthetic castor oil".
 
Werner:

"In short: Poly(ethylene)glycols form aggressive acids during combustion. Therefore, such oils are more additized to corrosion protection. An alkaline additive is added. That neutralizes. It consumes itself in constant circulation. Measured to control the basic buffer, TBN (Toatal Base Number). "

What is the life span, in months, of the alkaline additive, or does it depend upon the amount of driving. I am just curious about this.
 
That depends on the amount of acid introduced. Short drive distances are very bad, long distances with oil temperatures >100 ° C are always good. An exact guideline can not be given for an A-engine, because these old engines have a bad combustion with many incompletely burned fuel residues. (Ethanol residue is bad!)

In large engines, oil samples are taken and the TBN is measured. A reading below TBN 2 (origin 5.5, for example) indicates that the corrosion protection has been used up.

In a classic car engine with oil filter, I would recommend an annual change interval. Our A engine due to the dirt removal max. 1000 ml. No matter which oil is filled in.
 
My low-tech observation is that whenever I changed from dino oil to synthetic it was necessary to turn down the idle. Standard guidance was to NEVER use synthetic on a fresh rebuild because the engine will not break in. Also noticed that engines on a long and steady diet of synthetic seem to exhibit better tolerances (less wear) when undergoing a perhaps unnecessary rebuild. General sentiment seems to be it does not make much difference which oil is used. If it really does not matter I would prefer to go the synthetic route in hope it will add longevity to my engine. That is also the recommendation of my grandkids for estate planning purposes - LOL.
 
Terry said:
I like Shell Rotella 15-40 changing at 800 to 1000 miles.
Terry
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Terry, what would it take for someone to convince you to use a different oil...or would you rather be dragged over burning coals than change to say 20w-50? :D
 
M2M said:
Terry, what would it take for someone to convince you to use a different oil...or would you rather be dragged over burning coals than change to say 20w-50? :D
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I don't know...... I used Aeroshell 15/50 in aircraft engines, 20 years ago, but they're air-cooled with large clearances. The 15/40 is working pretty well, I don't see any reason to change. I'm not alone in this, in another poll, the Shell Rotella was the most popular brand and weight used in model A s Then there's the ZDDP thing. What exactly is wrong with it?
Terry
 
Terry, the oil type "Rotella" is undoubtedly a good oil. But it is mainly tuned to diesel engines. Diesel fuel (say kerosene?) has good cleaning properties and corrosion protection, but forms a lot of soot. Therefore, Rotella oils have a little less corrosion protection and a little more detergent.

Another advantage is that the combustion residues carbon remain relatively soft.

You do not do anything wrong with your A-machine, the engine will drive so long like with an other premium oil. But there are modern oils with more benefit.

(Remark: I have to say now that I developed the synthetic "AeroSynth" oil. Therefore I'm not neutral, so I prefer synthesis oils because of the belief.)
 
Witches tales re synthetic oil:
> Synthetic oil degrades gaskets. False! My engines have cork, paper, silicone composition and copper gasket materials. They have not been affected by synthetic oil;
> Synthetic oil leaks excessively. False! 10W30 and 10W40 synthetic oils have the same flow mechanics as 10W30 and 10W40 non-synthetic oils;
> Synthetic oil is harmful to babbitt bearings. False! I have an engine nearing 50,000 miles of running with synthetic oil, and the babbitt bearings are fine;
> Synthetic oil doesn't keep the engine clean. False! Synthetic oil stays cleaner longer than non-synthetic oil because synthetic oil substantially reduces wear, especially wear of the cylinder walls;
> Synthetic oil is too expensive. False! I use Walmart's Super Tech full synthetic oil costing $17.56 for 5 quarts. On a newly rebuilt engine, I use Shell's Rotella non-synthetic until the piston rings are seated;
> Synthetic oil needs changing every 500 miles. False! My habit is to change the oil once a year regardless of the miles driven. It is a rare occasion when one of my Model A's accumulates over 2500 miles in a year. However, even if one of my Model A's accumulated 10,000 miles, I would only change the oil once per year.






 
Hallo Bob. What you write about synthetic motor oils is mostly correct. But not this assessment:
Synthetic oil needs changing every 500 miles. False! My habit is to change the oil once a year regardless of the miles driven. It is a rare occasion when one of my Model A's accumulate over 2500 miles in a year. However, even if one of my Model A's accumulated 10,000 miles, I would only change the oil once a year.
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Regardless of which engine oil is used, the change intervals are always very short for a motor without a fine oil filter. This is because dirt such as dust and combustion residues, soot, oxidation, etc. is constantly pumped through and sprayed in the oil circuit and can thus increase friction wear. That is very bad for all camps!

In the filterless A, the oil is not changed because it has gotten worse, but because all the dirt remains in it. It must canged in short intervalls.
 
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