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An alternative way to monitor V12 cat ingestion - oil analysis
Plenty of threads exist on the risk of ingestion of catalytic converter material from the close-coupled primary cats on the V12 engines - and the subsequent destruction of the engine. Steve at aston1936.com has posted instructions on how to check the primary cats for deterioration of the internals. A couple of months ago I asked a question on Pistonheads as to whether anyone had performed oil analysis as an alternative tool to assess engine health, but I didn’t get a response. Perhaps oil analysis is less common in the UK where the majority of PH members are.
Recently I changed the oil in my 2015 DB9 and sent off a sample of the used oil to Blackstone Labs. Today I received my results - see attached. The absence of elemental silicon (from cat ceramic material), insolubles (same), and low levels of iron and aluminum (from engine wear) all point to the absence of cat material ingestion. To me this is just as good as an inspection of the cat honeycomb surface.
How reliable are the oil test results to gauge a potential cat ingestion?
Is it "as good as" the internal inspection? Or close enough that you can rely on these?
Hm - in order to detect catalyst residuals in the oil, they would need to get there first.
That means ceramic catalyst parts beiing sucked back into the combustion chamber, grinded down by the pistons and sqeezed between piston and liner to get into the engine oil.
Just imagine what these sharp-edged parts will do an their way.
An oil test makes sense to deduce the state of the bearing shells, but for the above? I don't think so.
Well no doubt that it is a “lagging indicator” rather than a “leading indicator”, but how is it different from inspecting the leading surface (closest to the engine) of the catalytic matrix to see if there is any sign of erosion? If there is, wouldn’t it similarly be too late?
In theory the oil analysis could also detect and flag the presence of fuel dilution of the oil, which would arise if you had a misfiring cylinder or two. Now that would be a leading indicator as it’s the excess fuel from one or more misfiring cylinders that causes cat damage in the first place.
