I realise this is a strange looking question!

I'm in a country where many local mechanics unfortunately have a bad reputation for creating small problems while fixing other problems in order to get repeat custom. There's no real system of regulation, accreditation or formal training here. I'm pretty sure I had this problem with one garage, who I no longer use, and I'm currently working with a new mechanic who's prepared to come out to me rather than taking a car to a garage, which reduces the risks.

I've had a strange problem where about an hour after he left, having done a rudimentary fix on a transmission fluid pan leak, the car stopped starting (but did run fine 10 minutes after he left). I suspect one part of the problem might be small amounts of oil I've found in the spark plug wells, something I've not seen in this car before. This could be from an innocent small leak, or, it's the sort of thing a rogue could do quietly when I wasn't looking. He sounded less than surprised when I mentioned the problem to him just now.

Suppose someone unscrupulous did pour small amounts of oil into spark plug wells. Is this something that would typically cause car-non-starting problems immediately, or might it in stop the spark plugs operating only after a certain amount of time (e.g. for the oil to seep in), or perhaps only after the engine has run a few times (e.g. needing the motion of the engine to foul the spark plug gap)? Or maybe I'm wrong in thinking that oil in the spark plug wells is something that could stop an engine firing on its own?

  • 1
    Do all of the spark plug holes now have oil in them? What type of engine is this (4-cylinder or V6/8)? Oil in the spark plug holes will not automagically kill an engine. I've seen valve cover leaks which would dump oil down onto spark plugs and the vehicle would run like that for a long time (months) without issue. I'm betting there is something else amiss here. May 5, 2016 at 11:14
  • Four cylinder, all had a small amount as far as I could tell. May 5, 2016 at 11:15
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    Does the oil look fresh? Can you identify where it might have come from? Oil leaks down (yes, gravity still works on vehicles as well). It had to have ended up in the spark plug wells somehow. If there is no clear and obvious path, your mechanic may have done something unscrupulous. If there is a clear path, don't blame him out of hand. Really, if I were you, I'd purchase some hand tools and start figuring this stuff out for yourself. You've made the right first step in asking questions here. We can help you in most cases with the right information. May 5, 2016 at 11:26
  • Ha, I'm trying, but part of the problem is that finding good tools out here isn't easy either! In particular I haven't yet found anywhere selling a long enough spark socket tool. They're recessed about 25cm, which limits what I can do. The oil looks old, virtually 50% grime, but there's an abundance of dust everywhere here so it wouldn't have taken much time at all to mix with dirt and become grimy. I don't think I'm yet qualified to judge if there's any alternate source of the leak, I'm reading up as best I can, there isn't one I can see, but I might well be overlooking something. May 5, 2016 at 11:32
  • Just ask your question directly next time. Give us pictures. Help us help you. May 5, 2016 at 11:37

1 Answer 1


If the plug wire was old and not sealing around the plug then you cold experience misfires not necessarily a no start. A lot of cars run fine with oil in the plug well from bad tube seals. Subarus are notorious for this.

  • Just checking I understood correctly: you're saying oil in the spark plug wells could cause sporadic misfiring progressively worsening over time, but not absolute, consistent failure to fire? May 5, 2016 at 14:03
  • @user568458 correct
    – Ben
    May 5, 2016 at 14:04

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