Aeroshell 100 vs w100

[photofly]

I found a case of Aeroshell Oil 100 in the basement; what are the downsides of using that vs the W type?

[Colonel Sanders]

100 is mineral (break-in) oil.

W100 is (normal) ashless dispersant summer weight oil.

NB W100 is equivalent in viscosity to SAE 50W. The
location of W matters.

[photofly]

Sorry, yes - w100. What will running 25 hours on mineral oil do? It can't be that bad, as I did exactly that while breaking in a cylinder.

[Spandau]

You can always use straight mineral oil. If you replaced a cylinder tomorrow it's what you would be using anyway. Years ago (think LONG time ago but same galaxy) before there was detergent oil, all oil was mineral oil. Detergent oil (W100) helps keep the engine clean internally but 25 hrs on straight oil won't hurt anything.

What kind of engine and do you have a filter?

[photofly]

TCM IO-470F, and yes, a spin-on filter.

[Spandau]

Straight mineral oil doesn't have a shelf life and there's nothing in it to settle out. You could use it, but maybe it would be better to put it up on the shelf for the day you change another jug? Either way it's fine.

[Colonel Sanders]

Expect carbon deposits to accumulate faster
with mineral oil.

[Colonel Sanders]

Some more info on this:

http://www.shell.com/global/products-se ... 71255.html

Long Term Operation on Straight Mineral Oils.

It is perfectly possible to run engines permanently on straight mineral oils but, as straight mineral oils do not contain any additives, they tend to cause deposits to form in the engine. The "W" ashless dispersant oils contain an additive that is designed to keep particles separated so that they do not congregate to form a large mass.

If these particles are kept separated then they are less likely to block an oil passage and deposit inside the engine. If the filter is of the relatively efficient cartridge type then the small, dispersed debris will be removed by the filter element. It is these particles in suspension that makes an oil appear black.

If straight mineral oils are used, then the oil tends to appear relatively clean but carbon and other particulates deposit inside the engine on casings etc. This is not too much of a problem unless you later encourage these deposits to loosen.

Changing onto an ashless dispersant oil after a significant build up of this deposit has occurred can cause this to happen. The dispersant additive can act like a detergent and clean out the inside of the engine. This normally results in an abnormally high level of filter deposits after the period of change over, so care should be taken to monitor this.

The critical time period for a significant deposit to occur inside an engine running on straight mineral oil depends on the individual engine type, operating temperature, flight profiles etc. but is normally around the 300 - 400 hour mark.

If your engine has run for this length of time on straight oil and you convert onto "W" (or ashless dispersant) oil, then take care to monitor your filter more frequently for signs of blockage. If your has not done this number of hours then you are reasonably free to choose whichever oil you see fit and don't worry too much.

http://generalaviationnews.com/2013/05/ ... uld-i-use/

The two most common questions that I still get are:

1. What oil should I use in my aircraft engine? And
2. Are different brands and grades of oils compatible?

First is straight mineral oil that meets the SAE J-1966 and Mil-L-6082E specification. The second is single grade ashless dispersant or AD oils that meet the SAE J-1899 and MIL-L-22851 D specification. The third type are multi-grade oils that meet the same SAE J-1899 and Mil-L-22851D specification. The last type of oils meet the same spec as the AD and multi-grade oils, but also contain the Lycoming LW 16702 additive or equivalent and are referred to as anti-wear oils.

So are these oils all compatible with the other choices? Well, usually yes, but there are some notable exceptions.

The straight mineral oils are usually used only for break-in of new engines. To determine which oil to use when breaking in your new engine, always check with your manufacturer or rebuilder.

Some people will use straight mineral oil for the entire life of the engine, which is legal. But this can lead to problems if the aircraft is sold and the new owners change to an AD oil. The AD oil can loosen up some carbon deposits, which can plug screens and filters, causing oil flow problems and even engine failure. Problems may only occur in, say, 20% of the change overs, but that is a significant level.

The big question is what is the limit in hours after which it is not advisable to switch to an AD oil? There is no hard and fast limit here because it depends on how the plane was flown and maintained. My best guess would be to not change over an aircraft after 200 to 300 hours — and even then monitor the oil screens and filters very carefully.

If you lose a cylinder mid TBO, you can switch from AD oil back to a mineral oil for a few hours, and then switch back to AD oil. The problem occurs from extended operation on the mineral oil, so always determine which type of oil was used when buying a used aircraft.

[black hole]

years ago straight 100 was used in radial engines; because you where constantly changing jugs and there was no need to change oils.

BH

[AirFrame]

years ago straight 100 was used in radial engines; because you where constantly changing jugs and there was no need to change oils.

Well, that, and the fact that radials are really better described as sieves as all of it will end up on the floor under the engine eventually if you just let it sit there. Topping up before every flight is normal, so you're really going through it faster than it can degrade.

[Colonel Sanders]

If you're going to live with a radial engine,
order a 55 gal drum of W120 (I am not a fan
of the ubiquitous 25w60 multi-vis for radials)
which you will measure oil for (and add) in
units of gallons ...

And also order a 55 gal drum of mineral spirits
and some bales of rags so that you can remove
the above W120 waste oil from the cowlings and
aircraft

I like how the W120 sticks to the top cylinders
during periods of inactivity. Also I prefer it for
the all-important bearings.

[goingmach_1]

[quote="Spandau"]You can always use straight mineral oil. If you replaced a cylinder tomorrow it's what you would be using anyway. Years ago (think LONG time ago but same galaxy) before there was detergent oil, all oil was mineral oil. Detergent oil (W100) helps keep the engine clean internally but 25 hrs on straight oil won't hurt anything.

They have not used detergent in oil since the seventy's.

[CpnCrunch]

You can always use straight mineral oil. If you replaced a cylinder tomorrow it's what you would be using anyway. Years ago (think LONG time ago but same galaxy) before there was detergent oil, all oil was mineral oil. Detergent oil (W100) helps keep the engine clean internally but 25 hrs on straight oil won't hurt anything.

They have not used detergent in oil since the seventy's.

All automotive gasoline has detergents, but avgas doesn't contain any. Perhaps that explains why aircraft engines seem to have more problems with plugged up exhaust valves. (I guess the auto-mixture control on cars helps too, compared to the typical pilot who doesn't bother leaning on the ground).

[Spandau]

You can always use straight mineral oil. If you replaced a cylinder tomorrow it's what you would be using anyway. Years ago (think LONG time ago but same galaxy) before there was detergent oil, all oil was mineral oil. Detergent oil (W100) helps keep the engine clean internally but 25 hrs on straight oil won't hurt anything.

They have not used detergent in oil since the seventy's.

Quite right! I was using "detergent" and "dispersant" interchangeably. My bad.