Harry don,t fix it, there ain,t nothing wrong and no you do not have to start removing the engines every few months and taking them apart for cleaning, that would be silly.

Yes the varnish is a residue from the castor and the higher the castor content of the fuel the more you will see this darkening on the external portion of engine. You said you use Omega fuel, If I am not mistaken Omega uses an oil package that consist of around one third of the oil content is castor and the balance is synthetic. Someone please correct me if I am wrong, I do not use morgan fuels.

Now some of the Morgan fuel have no castor and many blenders have fuels using oil packages that consist of only around two or three percent of the oil is castor and that is what a lot of us use.

Yes some castor is desirable as it provides a greater safety margin of a few degrees before it breaks down. This for those time when we mess up and have a lean run for various reasons.

The reason your LA 40 throws more oil is plain bering engines love to throw oil out around the crankshaft expecially as they wear. This is normal and not a problem.

The bottom line is Don,t fix it, if its not broke. If it throttles and runs well then its not broke.

John