[woofa.express]

Originally Posted by woofa.express

Yes Werner, I'd like to have your comments, however let me write, tomorrow, and I'll give you my thoughts and reasons and more details on oil types. cheers, gary

Rotor wrench had some pertinent comments on the use of Synthetic oils also.


Further to mycomments on Synthetic oil.

Following my input on synthetic oil I received a difference of opinion from my friend Mark and an enquiry from Werner, so please let me elaborate on my experience and reasoning.
The engine I had my experience on was a Continental IO520 in my Beech Bonanza. The I means injected and the O is normally aspirated, the 520 is the engine cubic capacity of the engine in cubic inches.
In all piston aeroplanes one has control on the fuel mixture for as one ascends the air becomes less dense thus the fuel needs to be leaned. It is recommended practice to run the mixture so as the exhaust gas temperature is 50 degrees F rich of peak temperature. Thus plugs and pistons will carbon over time. In past years avgas contained tetraethyl lead, and I think the same in motor spirit also. This created a build up of this lead in the cavity of the plugs and needed cleaning regularly. These days many pilots run 50 degrees lean of peak exhaust gas temperature and many have damaged their engines to the extent they need rebuilding. The reason being they should reduce power to accommodate this practice and they aren’t doing so. There are two traditional types of oil for these engines. 1, normal mineral oil which is recommended for newly overhauled engines, it has better lubricating properties, and 2, detergent oil which scavenges carbon. I found the synthetic oil was not scavenging the carbon so I returned to detergent oil and it was black in an abnormally short period. I continued to change at short intervals until normality returned. I might add there is one way to clean all the carbon out of these engines. Fill the fuel tanks with Jet fuel (kero) and they become instantly clean, however the engines fail on or shortly after takeoff.
On radial engines it is common practice to keep the mixture lean on the low altitudes where I am accustomed to operating however I did lean off a little. I’d take the aeroplane for a flight at night and see big blueflame which is unburned fuel. I’d lean off until the blue diminished but remained blue. I’d make a note or mark on the throttle quadrant and lean the mixture after takeoff to that position. On oil burn, I once bought 18x44gals of oil then took a Penzoil agency and lost it when I was told I didn’t purchase sufficient for an agency. I had purchased 72X44gals. The burn was about 1 gal per hour on a newly rebuilt engine which when settled in about 3 gals a day.
On gas turbine engines (jet) the mixture is controlled by a fuel control unit. This requires no pilot input. I thought it was Christmas when I purchased my turbine Airtractor. Easy engine management plus pilot comfort knowing engine failure was most unlikely. (Did you realise the big fan up front keeps the pilot cool, for when it stops the pilot gets very sweaty very quickly).Turbines use synthetic oil, it doesn’t get black and the reason is because it doesn’t get exposure to the fire place.The burn is less than 1 quart for a days work.
Maybe I should try synthetic oil in my town car but I would need convincing it has an advantage in a not so close tolerance built Model A engine.We are told so many lies by governments and commercial product manufactures I have become a sceptical person.
Are you sceptical? Do you believe all you are told?