There is little correlation between car engines and most aircraft engines. The problem with car engines is acid build up caused by low oil temps not boiling off the condensate during each use. The water combines with the sulphur compounds from combustion and forming sulfuric acid among a witches brew of chemicals that are not associated with lubrication. The oil in the bottle or can comes with several chemicals that will neutralize some volume of acid. Once it does that, additional acid is free to do the bad mojo on the light alloys in the engine. Channels in the bearing faces. Blackend stripes around edges of bearings, rough surfaces on normally smooth die castings and so on. It is seldom that a car sits idle for more than a week.
It is the reverse for aircraft. A month off is not uncommon. The rotary with its hotter oil soon after startup has no problem boiling off water based products. It has minimal crankcase volume and on cool down sucks in only a small volume of humidified air, so less condensate than a piston aircraft engine. You should put a filter on your breather, because it does suck air into itself on cool down.
I have been gifted cars owned by girls that have never had the oil changed. Of course the engines were seized. The breath of Cesar problem. (Evidence of the first oil will always be there)
The object of changing the oil, is to dispose of the acid and renew the anti acid package in the oil. At the same time the other products of combustion that have slipped by the seals are removed as well. But the hot oil of the rotary is a big help so long as it runs long enough to get the oil hot. If you have a screw together filter housing in the drain from the reduction box containing a magnet to stop any steel being dropped off the gears, (no element, just the magnet) then an annual oil change sounds perfectly acceptable. The engine is under no strain at all and specialty oils are of little value. Use whatever is best for the gear box. A car racing oil for its extra anti acid package and extra zink anti scuff compounds would be better. And a separate oil supply for the rotors of 2 cycle oil would keep the housings clean and the seals free in their grooves.
If you use the Oil metering pump, the crank case oil will be dropped into the rotor housings. Regular street oil resists burning and leaves behind unburned crap from the multi grade plastics, in the housings, fouling the apex seals. If you use the OMP, stick to straight wt. oils. Racing oils make it worse as they resist burning or even breakdown to higher temps. Synthetics don't burn at all and are a bad choice for OMP use. You can leave the OMP on and cut into the passage in the front cover anywhere its handy and install a dash 3 fitting and run 2 cycle oil from a bottle on the fire wall. Plug the oil passage at the face where it connects with the front iron. Now you can run any crank case oil and not worry about the apex seals.
I used Redline synthetic 40 wt. racing oil in the crank case of the race car. The top oil was Redline synthetic racing 2 cycle oil (for dirt bikes) and never a failure. No wear on apex seals (soft carbon). I changed oil every 4 races, about 8 hours or a bit less. The pretty green oil (not red?) would be black after 4 weekends. Engine was used between 7,500 and 9,600 RPM. Oil pressure is 100 pounds. oil temp is 180 to 190 (hot day) and water 160 -180- (hot day) If we could not get to 160 we put the thermostat in it.
Lynn E. Hanover
So 15K at an average of 150 MPH would be 100 hrs…Most cars change at 3K to 7K I think…7.5K would get you about 50 hours..??
There is no stop and go to build up water and stuff. I bet you could get 100 hours on 12 quarts of Mobil 1 with no adverse effects.
What do you think, Lynn?
Bill B