[woofa.express]

I put my thoughts on "Synthetic oils" and for those of you who may miss it I have pasted it here as well.

Synthetic oil ?

I seem to have a different opinion to other users. A buddy spoke about the positive benefits of synthetic oil in his aeroplane so I tried it in mine. The oil remained clean and after quite a number of hours I realised it wasn’t scavenging the carbon. I returned to the usual detergent oil and it got very black very quickly. I continued to change frequently until normality returned.
It is for this reason I never used it again. Has the composition changed? Or am I being obstinate? I have an open mind to logical criticism and positive suggestion.

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 oiltypes. cheers, gary

Rotor wrench also had some very pertinent comments on the subject as well.


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 cubic inch capacity of the engine.
In all piston aeroplanes one has control on the fuel mixture for as one ascends the air becomes less dense thus the fuel requires leaning. 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 the oil 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 the big blue flame which is unburned fuel. I’d lean off until the blue diminished butremained 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?