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I just did an oil change on my 1995 Nissan Altima, and noticed that the gasket on my dipstick does not make a seal inside the dipstick tube. The inside diameter of the tube is maybe 3/32 of an inch larger than the dipstick gasket. I don't know if this is how the car came or if this is an aftermarket dipstick. The gasket is made of rubber and appears to be in good condition. It's been this way for at least 6,000 miles, as that's when I last had the oil changed. Though, for all I know, it could have been this way for all of its 145,000 miles.

It's a 20 year old car and, accordingly, it has some issues. The idle occasionally fluctuates, and the exhaust smells a little rich. Overall, though, it runs good. Is the non-sealing dipstick a big problem? Should I expect significant improvement or extended engine life if I manage to find a good replacement?

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It's not a huge deal. The biggest thing you'd be looking for is if there is leakage from there. It's not going to be causing any running issues or any such.

I think the biggest thing would be if the stick was fitting deeper into the hole and giving you a false reading as far as oil level. If it's too low in the hole, it would appear you'd have more oil than you actually do. Not that it would be off by a huge amount, maybe a couple of ounces. Finding a new replacement wouldn't be a bad thing, but it's not going to affect how the engine runs or its longevity one way or the other.

  • wouldn't it allow unfiltered air to enter engine and reduce negative crank-case pressure? – philcolbourn Dec 20 '14 at 11:05
  • @philcolbourn ... While a very little bit of unfiltered air would get into the crank case area through the dipstick tube, it won't make a difference on this car. It has a breather and PCV valve which allows unfiltered air into the crankcase in the first place. The amount of air it could draw through this passage is negligible, anyway. Think small hole mostly filled with dipstick and covered, though not sealed. Unless it has a vacuum pump sucking the air out, there will not be an appreciable amount of negative pressure (vacuum) in the crankcase, either. – Pᴀᴜʟsᴛᴇʀ2 Dec 20 '14 at 11:36
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Your vehicle is designed (early) pre-OBD, so it will not affect the vehicle operation to any great extent, maybe a minor oil seepage. Later vehicles monitoring the air imput to the engine, ie OBD, the dipstick becomes important so it does not leak air. With OBD, a leaking dipstick seal would cause a mis-reading from the MAF, via the PCV, and cause rich running.

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