High mileage PSA: change your spark plugs!

[BlackCat81]

So my valve cover gaskets have been leaking for some time, and I finally got around to replacing them. Since the passenger side was apparently designed by Satan, I put it it off for way too long. Anyways, I figured while I was doing the gaskets, I'd throw a set of spark plugs in since it's obviously much easier to do at the same time. My M35 has 209,000 miles, and based on how it drove I assumed the plugs have been done at some point. The car was a bit sluggish, I always attributed it to the mileage and figured it was just old and tired. It ran very well, just kinda blah. Pulled the plugs out, and the majority of them had NO electrode left. I couldn't believe the car even ran, let alone ran well. After replacing them, the throttle response is a bajillion times better, it feels like a different car. Here's some obligatory pictures since we all love pictures.


One of the better ones next to a new one.

[Ilya]

Sent you a PM a few days ago about changing the plugs on my M56...need to do this but had a question.

I love installing new stuff like plugs, the butt dyno always makes me smile lol.

[BlackCat81]

Sent you a PM a few days ago about changing the plugs on my M56...need to do this but had a question.

I love installing new stuff like plugs, the butt dyno always makes me smile lol.

Ah, I'll check. I never get notifications so I never know when I have one. I'll get back to ya.

[reefscape15]

Ok, going to do this on my 45 . Just picked it up with 145k on it so I'm sure it could use a tuneup

[BlackCat81]

Ok, going to do this on my 45 . Just picked it up with 145k on it so I'm sure it could use a tuneup

Be prepared for leaking spark plug tube gaskets at that mileage. I can't recall if you can get them separately from the whole valve cover on an M45, but if you can, you should be ready to pull the valve covers. If you pull a spark plug out and your socket is covered in oil, you'll know what I'm talking about.

[kmiles]

I changed out mine about three months ago at 120K. One of mine was missing the platinum tip, too. I've seen a steady increase in gas mileage and performance since replacing the plugs.