Mores thoughts on synoil

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Sep 11, 2003
North of Dallas Texas
Some of the makers and sellers of synthetic oils talk about the demanding requirements of aircraft turbine oil. Here is some info on turbine oil used on aircraft. The operating limits on oil temps for the C130 with MIL-L-23699, a Polyol Ester are; Normal temp range 60-85 degree C, 85-100 for no longer than 30 minutes, if oil temp exceeds 100 degrees for 5 minutes it is an engine shutdown condition. If oil temp is observed to exceed 150 degree, drain and system flush and sump plug inspection is required, with follow up inspection of magnetic sump plugs 100 hours later. So you can see that automobile and truck engines are much harder on oil than aircraft are. From an army Chopper flight manual;LOW ENGINE OIL PRESSURE/HIGH ENGINE OIL TEMPERATURE If the engine oil pressure is below 50 PSI or the temperature is above 107 degC - Land as soon as possible.
The C130 uses turbo-prop engines. I would think that actual turbofan jet engines would have much different operating parameters when it comes to oil temps.
True! a turbofan is different, it has less lubrication requirements as it doesn't have a gear reduction system for the propeller. The T56 RollsRoyce/Allison engine has two reduction gear assemblies, one spur and pinion and the other planetary. The turbine speed is 13200 rpm and the prop turns at 1000 rpm. Turbofans don't have that kind of reduction gearing, they do have a reduction gear drive for the engine accessories.
Interesting stuff! I consulted with a jet pilot friend, asking this q: Robert: Do you monitor oil temp in your turbines? What is a typical value? Typical maintenence interval? Pilotbraden: We most certainly do monitor it. The green arc on the gauge is 40-55 degrees centigrade on the low side to 125-150 on the high side. Change intervals range from 200 hours on the low side to 800 hours on the high side with a filter change at one or two mid time intervals. We use exxon 2380 or BP 2380 in everything that I have flown but there are a multitude of others out there.
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