On 3/25/08, = Tracy Crook <tracy@rotar= yaviation.com> wrote:

Lynn's got it right in my view. If your're looking for a= number, I change between 50 and 70 hours using Synthetic. I go for t= he 15W - 50 Mobile 1 cause it has more Zinc for the gears & bearings th= an the lighter weights. Straight 40W Redline would be even bett= er but I can't get it at Walmart and I'm cheap.

BTW, I use a 4 qt sump even on the 20B. I don't understand t= he appeal of great big oil pans. Why carry all that extra weight?&nbs= p; Even if it means changing oil more often, I'd go for a s= maller pan. On a related subject, I get asked all the time abou= t G-forces affecting oil pickup in the pan in an airplane and the need for = a deeper, bigger pan. My standard answer is that your grandmothers st= ation wagon experiences more lateral G than your airplane ever will (unless= you happen to be Sean Tucker).

Sorry for the sermon, I just got asked that again <G>.

Tracy

On Tue, Mar 25, 2008 at 11:01 AM, Greg Ward <= gregw@onestopdesign.biz> = wrote:

Hey Lynn and Mark;

So what would the consensus be as the only differ= ence between my setup and Mark's is that I am using a fixed pitch prop?= Type of oil and frequency of change would be the question, especiall= y with the redrive. Tracy?

Greg

----- Original Message -----

From: Mark Steitle=

To: Rotary motors in aircr= aft

Sent: Tuesday, March 25, 2008 2:31 A= M

Subject: [FlyRotary] Re: Oil Change = Interval

Lynn,

Thanks for the great summary on oil. I guess I sho= uld have provided a bit more information on my first posting. This is= a n/a 3-rotor with a 2.85:1.0 RD2-C gearbox and an electric c/s prop. Norm= al engine operating range is between 5200 and 7000 rpm with the vast majori= ty of time spent in the 5000 - 6000 range. I may briefly hit 7200-730= 0 rpm on takeoff roll, but that's only for a few seconds until the prop= bites. Cruise flight is usually around 5200 rpm. The OMP has b= een removed and blocked off and I pre-mix a 50-50 blend of 2-stroke and MMO= . Living in Texas, my oil temps are high enough that I'm not too = worried about moisture buildup. The airplane is kept in a closed hang= ar and I try to fly at least an hour or two every weekend. One of my = concerns was the RD2-C. Is it happy with annual oil changes?

Can you provide a source for the inline magnet for the psru?
=
Thanks,

Mark S.

On Tue, Mar 25, 2008 at 1:59 AM, <Lehanover@aol.com> wrote:

There is little correlation between car engines and most aircraft engi= nes. 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 w= itches brew of chemicals that are not associated with lubrication. Th= e oil in the bottle or can comes with several chemicals that will neutraliz= e 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 smoo= th 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 rotar= y with its hotter oil soon after startup has no problem boiling off water b= ased products. It has minimal crankcase volume and on cool down sucks in on= ly a small volume of humidified air, so less condensate than a piston aircr= aft 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 cha= nged. Of course the engines were seized. The breath of Cesar problem. (Evid= ence of the first oil will always be there)

The object of changing the oil, is to dispose of the acid and renew th= e 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 g= ears, (no element, just the magnet) then an annual oil change sounds perfec= tly acceptable. The engine is under no strain at all and specialty oil= s 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 wou= ld 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 i= nto the rotor housings. Regular street oil resists burning and leaves behin= d 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 ma= ke it worse as they resist burning or even breakdown to higher temps. Synth= etics 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 th= e apex seals.

I used Redline synthetic 40 wt. racing oil in the crank case of the ra= ce car. The top oil was Redline synthetic racing 2 cycle oil (for dirt bike= s) 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

In a message dated 3/25/2008 12:10:12 A.M. Eastern Daylight Time, bbradburry@bellsouth.net writes= :

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