-------------- Original message from Lynn Hanover <lehanover@gmail.com>: --------------

In olden times the thin oil was by the stove, and the thick oil was over there by the door, except in the summer time when thick oil was not available. Then Castrol invented thick oil for the summer time.

 

The object of breakin oil was to provide a period of low stress running to level the poured babbit bearings

before great stress was applied. Just yesterday I assembled a 144 cubic inch Ford Falcon engine, and one of the instructions is to smack the center main cap (number three) fore and aft to center up the thrust flanges. The thrust bearing is in the number three main bearing rather than the rear main as is the normal case.

 

You also do a similar move on the rod caps as there is a dismal cap alignment system. So, you really do need a (plastic) hammer to build a Ford engine. Quality is job one here at Ford.

 

The rotary has no poured bearings. The bearings are so big for the stress involved that even screaming the engines in racing seldom causes bearing problems. The comment about a frew hundred more RPM after a few hours of running is exactly the correct observation. The side seals (soft cast iron) begin to seal just a bit better, as they develop a smooth shiny surface to run against the Nitrided cast irons. 

 

The stock oil pump puts out 71 pounds in early 13Bs and 12As or 115 pounds in FD (twin turbos) with a red line of 9,000 RPM. The object of higher than stock oil pressure is to move heated oil off of the bearing face. That soft grey stuff on the bearing surface has a low melting temperature and you don't want it to melt and move around the bearing. Ever notice the edges of a highly stressed bearing have little flakes of silver building up? 

 

You cannot cool a bearing face with scalding hot oil. That is why I often whine about oil temps being too high. 

 

Multi grade oils have long polymer chains that link up when heated to increase flow resistance

(thick oil?). So you can build a cold weather oil with good cold flow, and still maintain good oil pressure at operating temps when those chains link up. Like a 5 W 50 oil where the actual oil is a 5 weight Easy pouring oil and it has a lot of plastic in it to make it act like 50 weight oil at operating temps. 

 

Oil that can obsorb energy and give up energy quickly is good. Oil that has great anti-scuff compounds is good. Oil that has a high film strength is good. Oil that does not foam up is good. Foamed oil is full of air, and becomes an insulator, and the air displaces the oil, so lubrication is reduced. The rotary has an oil foaming problem.

 

If you maintain the stock oil injection pump (metering pump) you might want an oil with very little polymer content. Like a straight weight conventional oil. Just don't rev it up when its ice cold. Synthetic oils just about will not burn, or the burn is incomplete, and make a slimy mess in the exhaust system. If you use the OMP but feed it a real 2 cycle oil (designed to burn cleanly) then you can use a synthetic crank case oil. Or, if you premix your top oil instead of using the OMP, you can use a real 2 cycle oil, and get a nice clean burn.  

 

Racing oils have more zink and, or, zink like compounds, have high film strength, and lots of antifoaming agents. Are made from conventional base stocks and in straight weights have very few polymers. Are available everywhere and not expensive. Not as much as synthetics anyway.

 

I use 40 weight RedLine synthetic in the sump (dry sump reserve tank) and RedLine 2 cycle synthetic as the premix at one ounce per galon of 93 octane (no alcohol) pump gas. The engines are only used between 7,500 and 9,600 RPM. No oil related failures since 1980.

 

So, a good break in oil would be one that does not lubricate well, for our use. All we need is a bit better sealing, and that will come to pass in a few weekends for me, or a few months of use for an airplane. 

 

When it is time to fly put in the good oil, whatever you think that might be. I would use a straight weight (40 wt.) Valvolene racing with the OMP working. Or a sythetic 40 wt. With a 2 cycle for a premix. 

 

Any conventional straight weight (30wt.) motor oil for breakin is fine. I do 2 hours at 2,200 RPM for all new seals. Then open the filter and look at the crap you left in the engine, and look for bearing material.  

 

Straight 40 weight oil is fine. That 5W30 and 10W40 is street oil for 2,200 RPM street use. If you jump in and turn it up to 6,000 at full throttle for three hours, that is not street use.  

 

This information is free, and may be worth every penny.

 

Lynn E. Hanover