Bob:
I can't remember where I saw it, and it was years ago, but I remember
reading that the admonition not to use detergent oil on an old engine is
nonsense. The important thing is to have a good filter in place to snag
all the crud knocked loose. Also, prudence would indicate several prompt
oil changes after switching to the detergent oil.
I recently restored a TC engine that had sat idle for about 12 years.
Prior to that it had been run without any oil filter - the external
plumbing had been welded together to eliminate the filter! It was
incredibly filthy - so bad that for the first time in my many years of
working on engines, I took photos of the insides *before* I cleaned it up.
The vertical surfaces under the timing chain cover were coated with a layer
of gelatinous crud about 1/4" thick and the botton of the pan had about 1"
of this on top of a quarter inch of a very hard tar-like layer. I can well
imagine what modern detergent oil would look like after running thru this
engine (if I hadn't cleaned it out) but I would rather have done that than
have left the crud in there to produce indefinitely some low level of
contamination of a non-detergent oil.
I say, go with the soap!
Russ Wilson
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