Andy,
The Rod failures Ive read about arent lube related but due to the loads imposed by the high speed direction changes - they snap!
Re the ether I tend to think it may need to stay around 39% to get good throttling also with carefull use of high nitrate content 2.5-3% to get the rapid acceleration needed, no dought Davis has had many headaches getting it right and deservs to be heard on the subject. Diesels in cars is a whole new feild, vastly different to our aircraft engines which "typically" run in the 8-14,000 RPM range.
Stewart