Cheap (1,5$) spark plugs removed from my 5cyl turbo (Audi Avant Turbo Quattro AAN 1993) after 40 kkm. The gap increased from 0,65 (new) to 0,93 mm.
Can anything be said about the engine status judging by this picture (other than that the bad gas had tons of iron-based octane-increasing additives which gave the isolators such a color?)
Thanks.
They're a little dark. Maybe it's the gas, maybe the mixture is a little rich or maybe your burning a little oil. A compression test could help with the diagnosis.
Thank you, Doc! Am probably really burning some oil. With a turbo, especially such an old one, this appears unavoidable, cause the oil seal in the turbo is not 100% hermetical by design. However the volume of oil losses is negligible - never had to fill up any oil between changes yet.