Mixing W100 with 100
- Thread starter LSK
- Start date
- Joined
- Dec 5, 2010
- Messages
- 5,600
- Display Name
Display name:
GeorgeC
Thanks - I did use the search feature before posting without luck - must have typed in the wrong search words to find what I was looking for - specifically about mixing detergent and non-detergent - but I see a guy in the link you provided did just that without any known issues - thanks
NordicDave
En-Route
Does anyone else remember the episode of Airplane Repo when Mike Kennedy was taking a 172 Seaplane and dumping in a couple of quarts of automotive oil?
Tom-D
Taxi to Parking
- Joined
- Feb 23, 2005
- Messages
- 34,740
- Display Name
Display name:
Tom-D
it shouldn't matter.
Tell us why we use AD oils in a flat engine?
We understand the radial engine use it, but why do we ?
brien23
Pattern Altitude
How about automotive Synthetic Motor Oil.
Huckster79
Pattern Altitude
- Joined
- Nov 22, 2018
- Messages
- 2,396
- Display Name
Display name:
Huckster79
No don’t do it!
save your engine and ship it to me, I’ll PM you my address. Paying the shipping will be well worth the temptation of using it for you...
save your engine and ship it to me, I’ll PM you my address. Paying the shipping will be well worth the temptation of using it for you...
Tom-D
Taxi to Parking
- Joined
- Feb 23, 2005
- Messages
- 34,740
- Display Name
Display name:
Tom-D
If it was as thick enough to hold oil pressure, why wouldn't it work.
Snowmass
Line Up and Wait
As I recall straight synthetic was once sold for aircraft use but withdrawn as it caused damage due to chemical reactions with aircraft engines not found in auto engines. While I am not sure of the cause of this damage I am very sure that is once used and then stopped.
dmspilot
Final Approach
- Joined
- Oct 20, 2006
- Messages
- 6,190
- Display Name
Display name:
DISPLAY NAME
Mobil AV-1
Shell was one of the first to try synthetics in recips following their development of synthetic turbine oils. The problem was from the combustion by-products of the leaded avgas interacting with the synthetic base oil. The result basically glued the piston rings into their grooves causing increased excessive consumption and other issues.
- Joined
- Jun 13, 2008
- Messages
- 7,951
- Location
- Marietta, GA
- Display Name
Display name:
Drake the Outlaw
Didn’t suspend lead well and gunked up engines.
But for repositioning an airplane, I doubt harm would come of using full synthetic as a one time thing.
Tom-D
Taxi to Parking
- Joined
- Feb 23, 2005
- Messages
- 34,740
- Display Name
Display name:
Tom-D
the problem becomes the oil clearances of the aircraft engines are too big, then the oil pressure drops.
- Joined
- Jun 13, 2008
- Messages
- 7,951
- Location
- Marietta, GA
- Display Name
Display name:
Drake the Outlaw
No doubt, but that's a viscosity issue, not a synthetic/mineral issue.
Tom-D
Taxi to Parking
- Joined
- Feb 23, 2005
- Messages
- 34,740
- Display Name
Display name:
Tom-D
PaulMillner
Line Up and Wait
PaulMillner
Line Up and Wait
Well... non-compliant... automotive oil isn't listed on Lycoming or Continental's approved lubricants list.
Our engines are certified by Lycoming and Continental as having an oil consumption rate of nearly 1 quart an hour as acceptable. As you approach that burn rate, PCMO (passenger car motor oil) will leave quite a bit of ash deposit in the cylinders. Ash deposits can lead to pre-ignition, which can destroy an engine in seconds. That's generally considered worth avoiding.
Paul
PaulMillner
Line Up and Wait
The lead salts that are a byproduct of 100LL combustion end up in the blowby and thus in the oil. They are soluble in mineral oil (which is what makes up AD oil, and all but the synthetics) but NOT soluble in synthetic oil. This is why the Mobil AV1 failed so spectacularly... the engines sludged up with lead salts because the non-mineral oil couldn't carry it away.
Paul
Tom-D
Taxi to Parking
- Joined
- Feb 23, 2005
- Messages
- 34,740
- Display Name
Display name:
Tom-D
92 UL ?
Tom-D
Taxi to Parking
- Joined
- Feb 23, 2005
- Messages
- 34,740
- Display Name
Display name:
Tom-D
we run 115/145, in the P&W and wright 3350 and the D120, the ash never showed, the 1 qt per hour should not bother it. we did change plugs every 25 hours.
PaulMillner
Line Up and Wait
Well, there's a question mark... can I buy a verb for that question, Tom? Swift makes a 94UL, is that what you had in mind? Or...
https://www.swiftfuelsavgas.com/order-forml
Unleaded avgas, whether GAMI 100UL or lesser octane unleaded, should be compatible with synthetic oils; there will still be concerns about metallic ash from oil additives, so none of the manufacturers are likely to add PCMO (passenger car motor oil) to their approved lubricants list.
Paul
PaulMillner
Line Up and Wait
we run 115/145, in the P&W and wright 3350 and the D120, the ash never showed, the 1 qt per hour should not bother it. we did change plugs every 25 hours.
There's no ash attributable to the 8 grams/gallon of lead in 115/145. Beyond that, did you have a comment or a question?
bflynn
Final Approach
Tom-D
Taxi to Parking
- Joined
- Feb 23, 2005
- Messages
- 34,740
- Display Name
Display name:
Tom-D
I've seen plenty of lead in the 3350 Wright, and we use a lot of oil. but I've never seen any problems attributed ash.
So why worry about AD (Ashless oil) ?
Very long time we in aviation had to use a AD oil, that is an oil that contains very little or no sulphur due to metallic content.
Maybe when we used 5 gallon oil per hour we may have a problem, but when we use less than 1 qt. per hour I fail to see the problem.
Last edited:
PaulMillner
Line Up and Wait
Aren't you running straight mineral oil in that radial engine? There are no ash-producing additives in straight mineral oil.
It's not ashless oil; it's ashless *dispersant* oil... the dispersant is like a detergent, it keeps the contaminants in solution in the oil, so that they can be drained from the engine, instead of creating sludge inside the engine.
Uh, no. That's not what ashless dispersant implies... the sulfur content will correlate to the crude oil the base oil was refined from... and that is unrelated to metallic content. AD oil contains NO metallic additives to enhance lubrication performance. It does contain non-metallic additives, that are more expensive than their metallic equivalents.
I think that's because you may not be looking at the correct problem.
Tom-D
Taxi to Parking
- Joined
- Feb 23, 2005
- Messages
- 34,740
- Display Name
Display name:
Tom-D
You talk two different subjects in one statement. ashless, and dispersant.
Ashless, has to do with metal ash left behind when burned. That ash will induce hot spots causing pre-ignition.
Ashless does not contain sulphur the mineral that when burned produces the Ash. (thus ashless)
Dispersant, has to do with the ability of the oil to not be a detergent, Dispersant oil will not clean as they go detergents will.
The oil we ran in the willey Victors was a AD oil. Ashless Dispersant W120 weight.
Never talk about aviation oil when you are talking "detergents" because they are not allowed.
Dispersant oil allows the oil to drop heavy particles to fall out quickly, exactly what you want when you don't have a filter. Remember these aircraft engine did not have filters when the oil was used for years.
Last edited:
MuseChaser
Pattern Altitude
- Joined
- Feb 23, 2019
- Messages
- 2,038
- Display Name
Display name:
MuseChaser
If one had a mogas stc and used only unleaded, ethanol-free gas in a Lycoming o-320, would using full synthetic oil still be problematic? I have a friend who is an excellent mechanic argue that full synthetic oil is better for the engine, but three trusted a&ps have negated his opinion. Even though I have the mogas stc, I still use nothing but 100LL and the oil recommended by my A&P... I don't like to take chances, it's more convenient, and the cost differential isn't worth the risk. However, I have enough knowledge of and trust in my friend's experience to be curious if there's a case to be made for his assertion.
No, the subjects overlap. Sulphur isn't a metal. Dispersants and detergents do overlap. Some dispersants are detergents.
PaulMillner
Line Up and Wait
You've got that all pretty much wrong, Tom... but I can recognize when you've made up your mind...
Tom-D
Taxi to Parking
- Joined
- Feb 23, 2005
- Messages
- 34,740
- Display Name
Display name:
Tom-D
PaulMillner
Line Up and Wait
There's a couple of problems with Sinclair's page... presumably written by marketing, and not by engineering. The first clue is the reference to "preignition detonation" which is not a thing... pre-ignition and detonation are two different phenomenon that take place under different scenarios. Pre-ignition is definitely caused by ash deposits. Take a look at your copy of CF Taylor's "The Internal Combustion Engine in Theory and Practice" which is, as you likely know, the definitive text on engine design, even to this day.
Second, they call their oil "ashless" and then refer to its low ash content. Look, it's either ashless (and apparently it is not) or it's low ash. This compressor engine oil is apparently low-ash, which would not meet the aviation specification.
You didn't answer the question, Tom... are you using non-aviation compressor engine oil in radial engines? Or simply non-AD mineral oils?
Paul
Tom-D
Taxi to Parking
- Joined
- Feb 23, 2005
- Messages
- 34,740
- Display Name
Display name:
Tom-D
Tom-D
Taxi to Parking
- Joined
- Feb 23, 2005
- Messages
- 34,740
- Display Name
Display name:
Tom-D
the truck had a D-120 marked on it.
I ran Phillips W-65 when I ran the Warner, That was all we could get.
their page
https://phillips66lubricants.com/product/xc-aviation-oil/
I did not understand "compressor engine"
Last edited:
PaulMillner
Line Up and Wait
That depends on the synthetic. All the readily available oils are PCMO, passenger car motor oils, and hence include additives that form ash, which as discussed, is a very bad idea in an aviation engine.
Does he say why? Synthetics excel at very high engine temperatures, and very low ambient temperatures. I suspect your O320 is encountering neither of those... so why would a synthetic be better for YOUR application? The other problem is that if you EVER find you need to fuel with 100LL, the lead is not going to be carried by the engine oil, leading to engine sludging, that can be engine destroying.
Paul
PaulMillner
Line Up and Wait
See the Sinclair page you cited... the oil they're selling there is designed as a "natural gas engine oils." These are generally natural gas pipeline compressors... they are piston engine/compressors, with a few natural gas burning cylinders on the same crankshaft as several natural gas compression cylinders. Interestingly, the spark plugs in the engine cylinders are 18mm... they look just like our aviation spark plugs, and in fact share the same part number nomenclature as our aircraft plugs.
These engine-compressors are commonly over 1,000 HP... I think I've seen them as big as 4,000 HP... the engine cylinders provide the power to the crankshaft, the compression cylinders move the gas down the pipeline.
An aviation tie-in... in about 1989, I was flying my FG Cardinal from Texas to California for a Cessna Pilots Association weekend fly-in at Santa Maria. #3 cylinder's exhaust valve broke, necessitating that we land on a dirt road in the New Mexico desert, adjacent to such a natural gas compressor station. The four guys that worked there had homes there, with their wives and children. They were very kind to us, and actually drove us four hours over terrible dirt roads to Albuquerque to meet up with a mechanic.
After fixing the engine on the side of the dirt road, I gave all the workers airplane rides; one of them had never been up in any plane before. I also got a tour of the compressor station.
When I started with Chevron in 1975, we still had some of the engine-compressors in the refinery... on start up, they could backfire... that was an event that really got your attention, with a hundreds of horsepower of gas lighting off in the exhaust stack!
Tom-D
Taxi to Parking
- Joined
- Feb 23, 2005
- Messages
- 34,740
- Display Name
Display name:
Tom-D
as for their advertising
I know for a fact the the AD oil does not do what it says it does. Your advising says pretty much the same thing.
the engine pictured we removed by me in 2005 We know the owner used Aeroshell W100 sense new. It was 1" thick of sludge, He changed oil religiously at 25 hours.
my jeep was operated on Delow 15/40 detergent for 200k and it was clean as a new engine.
I know for a fact the the AD oil does not do what it says it does. Your advising says pretty much the same thing.
the engine pictured we removed by me in 2005 We know the owner used Aeroshell W100 sense new. It was 1" thick of sludge, He changed oil religiously at 25 hours.
my jeep was operated on Delow 15/40 detergent for 200k and it was clean as a new engine.
Attachments
Tom-D
Taxi to Parking
- Joined
- Feb 23, 2005
- Messages
- 34,740
- Display Name
Display name:
Tom-D
Simply pasted the wrong page.
Tom-D
Taxi to Parking
- Joined
- Feb 23, 2005
- Messages
- 34,740
- Display Name
Display name:
Tom-D
here's a better one,,
Phillips 66® Type A Aviation Oil is an ashless dispersant, single-grade engine oil specially formulated for use in aircraft piston engines. The ashless dispersant formulation helps minimize the formation of engine sludge, varnish, piston deposits and combustion chamber deposits, resulting in a much cleaner engine compared with the use of straight (non-dispersant) mineral oils.
and all the pages say about the same thing.. and it is simply a lie.
Every engine I tore down proves it, they all look the same. Full of sludge, and varnished over, on dispersant oil.
Detergent oil has the ingredients to keep the engine clean.
Last edited: