Greasers! You know who you are. You grease your own valves. Many of you know your engine better than your IA, and know that if an A&PIA sees the 10, or 14, or 18 zerk fittings on your engine and says, "that's all you have to do??" then he's not qualified to lube your engine. On certificated aircraft, always adhere to the manufacturer's recommendations. For additional vintage airplane documentation and information, please join and contact AAA/APM. Following are some popular engines which require manual lubrication for which the originally recommended rocker box grease may no longer be available. Have a qualified A&PIA determine whether Jewell Amber Oil Rocker Box Grease is suitable for you.
Most aviation engines designed or built before about 1931 had no provision for running engine oil to the valve train. This was not because it was an unheard-of practice to run oil upstairs, but because aircraft engines run at high loads continuously, they heated the oil too much. Improvement in cylinder head design and oil cooling in the early 1930's lead to engines where manual lubrication was no longer necessary. Owing largely to the Great Depression, re-tooling was too costly, and many early designs lingered in production through much of the 1930's.
So called low-melt #2 greases were, and still are a popular substitute. These are basically a two-part compound: base oil and fillers known as "soaps". They have a typical drop-point of about 430f. This is where they slide off heated metal -- no longer sticking -- a hot screw driver for example. This is where the grease "melts", which really means the grease separates. What they leave behind when they "melt" is a useless film about like WD40, because the base oil is very thin. When it cools, the base and the soaps do not blend again. After some heat-cycles, dry caked grease results.
Of course we now know that oil is the best lube upstairs, but that is not practical in most early rocker boxes because it just doesn't stay where its put for long enough. What Rocker box grease is basically, is gooey sticky oil, and if heated to drop point, will resume its original consistency when it cools. Genuine valve train greases differ from all other greases in being tacky and runny at the same time, with relatively high 'drop' and 'flash' points. Jewell Amber Oil is a genuine purpose-built lubricant, pure and thick, no fillers.
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