Tracy,

I just don't want to destroy the gearbox because I didn't change the oi= l often enough. Sounds like a plan.

Mark S.

On 3/25/08, Tracy= Crook <tracy@rotaryaviat= ion.com> wrote:=20

Lynn's got it right in my view. If your're looking for a number,=20= I change between 50 and 70 hours using Synthetic. I go for the 15W - 5= 0 Mobile 1 cause it has more Zinc for the gears & bearings than the ligh= ter weights. Straight 40W Redline would be even better 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 the ap= peal 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 smaller pan.= On a related subject, I get asked all the time about G-forces a= ffecting oil pickup in the pan in an airplane and the need for a deeper, big= ger pan. My standard answer is that your grandmothers station wagon ex= periences more lateral G than your airplane ever will (unless you happen to=20= 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> wrot= e:

Hey Lynn and Mark;

So what would the consensus be as the only differenc= e between my setup and Mark's is that I am using a fixed pitch prop? T= ype of oil and frequency of change would be the question, especially with th= e redrive. Tracy?

Greg

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

From: Mark Steitle

To: Rotary motors in aircraft<= /A>

Sent: Tuesday, March 25, 2008 2:31 AM=

Subject: [FlyRotary] Re: Oil Change I= nterval

Lynn,

Thanks for the great summary on oil. I guess I should have provided a=20= 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. Normal engine operating ra= nge is between 5200 and 7000 rpm with the vast majority of time spent in the= 5000 - 6000 range. I may briefly hit 7200-7300 rpm on takeoff roll, b= ut that's only for a few seconds until the prop bites. Cruise flight i= s usually around 5200 rpm. The OMP has been removed and blocked off an= d 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 hangar and I try to fly at least an hour=20= or two every weekend. One of my concerns was the RD2-C. Is it ha= ppy 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 engin= es. The problem with car engines is acid build up caused by low oil temps no= t boiling off the condensate during each use. The water combines with the su= lphur compounds from combustion and forming sulfuric acid among a witch= es 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 mo= jo on the light alloys in the engine. Channels in the bearing faces. Blacken= d stripes around edges of bearings, rough surfaces on normally smooth die ca= stings 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 bas= ed products. It has minimal crankcase volume and on cool down sucks in only=20= a small volume of humidified air, so less condensate than a piston aircraft=20= engine. You should put a filter on your breather, because it does suck=20= air into itself on cool down.

I have been gifted cars owned by girls that have never had the oil chan= ged. Of course the engines were seized. The breath of Cesar problem. (Eviden= ce 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 c= ombustion that have slipped by the seals are removed as well. But the hot oi= l of the rotary is a big help so long as it runs long enough to get the oil=20= hot. If you have a screw together filter housing in the drain from the reduc= tion box containing a magnet to stop any steel being dropped off the gears,=20= (no element, just the magnet) then an annual oil change sounds perfectly&nbs= p;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 i= ts extra anti acid package and extra zink anti scuff compounds would be bett= er. And a separate oil supply for the rotors of 2 cycle oil would keep the h= ousings clean and the seals free in their grooves.

If you use the Oil metering pump, the crank case oil will be dropped in= to the rotor housings. Regular street oil resists burning and leaves behind=20= unburned crap from the multi grade plastics, in the housings, fouling the ap= ex seals. If you use the OMP, stick to straight wt. oils. Racing oils make i= t 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=20= OMP on and cut into the passage in the front cover anywhere its handy a= nd install a dash 3 fitting and run 2 cycle oil from a bottle on the fire wa= ll. Plug the oil passage at the face where it connects with the front iron.&= nbsp;Now you can run any crank case oil and not worry about the apex seals.=20=

I used Redline synthetic 40 wt. racing oil in the crank case of the rac= e 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 eve= ry 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=20= RPM. Oil pressure is 100 pounds. oil temp is 180 to 190 (hot day) and water=20= 160 -180- (hot day) If we could not get to 160 we put the thermostat in it.<= /div>

Lynn E. Hanover

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

So 15K at an average of 150 MPH would be 100 hrs=E2=80=A6Most cars change a= t 3K to 7K I think=E2=80=A67.5K would get you about 50 hours..??

There is no stop and go to build up water and stuff. I bet you could=20= get 100 hours on 12 quarts of Mobil 1 with no adverse effects.=

What do you think, Lynn?

Bill B

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