Posted Tuesday, March 27, 2007 @ 04:40 AM  

In my opinion corrosion happens when parts are in old oil maybe with a high water pollution and old oil can desintegrate to build acids.
Limbach and Sauer say never store an engine with the engine oil but fill it with "conservation oil".

Patrick

Posted Sunday, January 13, 2008 @ 02:37 PM  

But if this is so there should perhaps be less acid build up but not zero. 20-hour oil is said to be "nasty stuff" and shouldn´t sit in an engine for too long, so maybe it´s best to do an extra oil change before the cold season or periods of less flying. How do you guys do?

Another question is whether to use thicker oil as advised in the article. Or perhaps molybdenium disulfide as mentioned by Bob as an oil additive? Anyone know under what name that is sold in Europe by the way?

The article can be found on:
http://www.avweb.com/news/savvyaviator/savvy_aviator_52_thinking_about_oil_changes_196730-1.html

Posted Thursday, November 20, 2008 @ 00:12 AM  

Winter inhibiting our engines.

Molybdenum disulphide is marketed in England as 'Molyslip' but.... It is only for lubrication when you have no oil pressure (ie, when your Fournier is upside-down). So far as I know, although it is advertised as reducing internal engine friction, it has no corrosion-inhibiting properties.

When I store my aeroplanes for the winter (generally six months of disuse) I change the oil.
In the Lycoming and Continental, I use AeroShell 15w50 multigrade, because it has the best corrosion inhibitors of all aviation multigrades (BP/Castrol information). And of course, I use a multigrade for all the obvious reasons (see above).

For the Fourniers I use 'Castrol GTX for older vehicles', which from memory is a 15/50 multigrade.
I do the same in my old Jaguar & Land Rovers.

In every case, I get the engine good and hot (at least a half-hour flight or drive) before draining out all the old oil, and then leave the oil to drain at least overnight, tipping up the aeroplane to ensure absolutely all the old oil is out of the engine.

Then I add the fresh new oil and run the engine for 30 seconds to a minute.
The idea is to circulate the new oil all around the engine in its cold, sticky state, but not to let the oil heat up at all.
Thus, I hope everything inside the engine is coated in thick, slow-dribbling oil, which should stay on the surfaces for several weeks.

Then I remove the spark plugs, spray thin oil or ACF50 into the cylinders and replace them with desiccant plugs.
Finally, tape up the exhausts, breather and intake to prevent fresh, damp air from entering the engine.

Go away.

Come back six months later.
Untape the engines, remove the desiccant plugs.
Crank or spin the propeller by hand until thirty seconds of oil pressure (boy, but this is hard work on the Fourniers and the Champ).
Clean & replace the spark plugs.
Start engine, run for five minutes.
Thorough visual external check.
Go fly/drive.
Try to ignore the fact that none of this is any good for my engines, but is the best that I can practically do.

Does anybody have any better/additional ideas?