One thing that engine oil labs do not test for that may be present in engines fuelled on B100 (it is a problem with engines fuelled on SVO/WVO is lube oil polymerization. In fact the first instance I saw of this was in a generator (rented for Burning Man) that had been run on homemade biodiesel.

Crankcase oil polymerization can occurr when there is excessive contamination of the "lube" oil by fuels that can polymerize (form long molecular chains similar in some ways to plastic). Excessive blowby, long idle times, and/or waiting too long to change crankcase oil can cause the crankcase oil to become too thick to flow thorugh the fuel system..or simply gel upon cooling enough to not flow to the oil pump pickup when the engine is restarted. Which ... needless to say (but as an engineer I have to say it) can cause catastrophic engine damage.

Several years ago I developed a simple test for this.


To test for crankcase oil polymerization:
1.Retain about a cup of the used lube oil in a small jar.

2.Seal it up and refigerate overnight.

3.Tilt the jar to see if the oil flows at all. Since refrigerators typically are set at between 37-45*F it may flow like molasses or tar...but it should still flow.

If it appears at all jello-like it indicates polymerization is ocurring in your lube oil and that you should increase the frequency of your oil changes. If it remains jello-like after warming to room temp you may have advanced ring coking and should immediately determine if this is severe using compression tests before major engine damage occurrs.