I switched out my bosch plat 4s they only had 15000 on them and from what I seen they were about gone. I didn't get a good pic of the electrode but have one of the whole plug. I don't know what this burn't haylow around the plug means. maybe you guys could tell me. On a side not my lower intake wasn't that dirty. I think cracking the secondaries helped from letting the gunk build up on the butterflys. The main ports past the injectors were sparkling clean. The secondary ports were so so clean. the upper was in pretty good shape also.
