Engine Deposits - Their Cause and Cure

How would you want an engine with combustion chambers clean as a whistle?
Deposits are what causes after-running and detonation (pinging), all else
being equal.

Many people are under the misimpression that rich fuel mixtures and
prolonged idling leave harmful carbon deposits. They're only half right.
This condition produces carbon deposits, but they are not harmful because
they are soft carbon deposits. You could wipe away carbon from rich
running and tick-over.

No, the baked on deposits that glow red hot is the real culprit. This
harmful condition is caused by your oil! Every engine has oil entering the
combustion chamber. It is essential for cylinder/piston/ring lubrication
and not to forget, valve-to-valve-guide lubrication. It is not normally
enought to see as smoke in the exhaust, but you can bet your boots oil does
indeed combust with the fuel-air mixture.

Combustion of automotive oil will leave deposits. Combustion of
"motorcycle" oil will leave deposits. Eventually you engine will ping,
lose power, overheat, and valves will stick, especially when you wind up
the revs. There is one type of oil, and only one type of oil that leaves
virtually no baked on deposits. That oil is described as "Commercial
Aviation Oil". It is available as "straight" or "A-D". It is available in
all common SAE viscosities and even in mult-viscosity, at slightly higher
cost. For most motorcycles, ask for "Commercial Aviation Oil #80 A-D".

C.A.O. #80 A-D is SAE 40 with non deposit forming additives. More detail:
#80 corresponds to the viscosity. #80 = SAE 40; #100 = SAE 50, and so on
#up and down the scale. A-D stands for "ashless-dispersant". Ashless
#means no deposits are formed when the oil is burned. Dispersant means
#dirt, metal particles, carbon etc. are suspended in the oil instead of
#deposited as sludge. Use Commercial Aviation Oil for long, trouble-free
#motorcycle engine life.

The trouble with auto or 'cycle oils is they have metallic-containing
additives which form hard, permanent deposits on the valves, pistons and
combustion chamber. You no doubt have encountered such intractable deposits
when trying to wire brush them off at valve-job servicing.

This important post has been brought to you by Nomen Nescio.

 

Nice way to void you warrantee or any possible claim to pay for engine
damage. Reminds me of the fellow that refused to pay Honda prices for an oil
filter for his new Goldwing. He bought a car oil filter, put it on and due
to the heat the oil filter started to come apart and clogged the oil
passages. He tried to get Honda to pay for it but they refused. It cost him
$8000 to fix his engine. I have also seen Ford put a brand new engine in a
car that had 65k miles on it and they did it for free. Why? Oil filter
failed. You can put 90 weight in an engine if you want, just don't expect
the manufacturer to do anything if or when your engine fails.

Here is something from Lycomings website.
http://www.lycoming.textron.com/main.jsp?
bodyPage=/support/publications/keyReprints/maintenance/moreAboutOil.html

Multiviscosity oils have also been added to the field of aviation products.
These oils cover a broad band of viscosity levels, and a number of them are
approved by the latest revision to Lycoming Service Instruction 1014. These
aviation grade, ashless dispersant (AD) oils have some definite advantages
when used during cold weather. Because they flow more easily in cold
temperatures, starting the engine is easier and lubrication of engine
components gets started more quickly. Unfortunately the additives that make
these oils capable of operation at all temperatures also tend to form carbon
products during hot weather operation when the oil usually runs at the high
end of the temperature spectrum. These products may settle out in the valve
guides and contribute to sticking valves. Therefore each owner or operator
should consider the type of operation the aircraft is used for and take
advantage of the qualities offered by multiviscosity oils while avoiding
their use if it may be the cause of potential problems.

So go ahead and run that aviation oil. It will be interesting to watch your
valves get sticky and carbon up.

Bottom line? Follow the manufaturers recommendatons to the letter.

pierce

 

man i wish I had Nomen Nescio's job...then I could sit around all day
and type up page upon page of crap that I know more knowledgable
people would just shoot down anyways...oh well

 

*PLONK*