Electrolysis between a steel drain plug and aluminum oil pan?

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Jan 30, 2023
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Our oil change place (a reputable transmission shop) told us that during an oil change on our 2012 Honda CR-V the threads in the aluminum oil pan had stripped due to electrolysis with the steel drain plug, and that our oil pan would need to be replaced for $1,100. However, everything I have checked online and with another mechanic indicates this is nonsense, that the only way this can occur is because of overtightening. Can electrolysis between the plug and pan actually destroy the oil pan threads?
 
It can if you had it sitting in salt water with a small current running through it otherwise I would say they stripped it and are trying to avoid replacement. You can also get repair plugs at the auto parts store. They have cutting threads just slightly larger than the original for $10 and they work very well.
 
I’ve paid for 2 oil changes in my life, both times my wife took the vehicle because I was out of town. The last one, 25 years ago, the shop stripped the drain plug. I was so 😡. I replaced the drain plug with an oversized plug with smaller drain hole like this one. It worked for several thousand miles and many changes later.


Just my $0.02
 
Our oil change place (a reputable transmission shop) told us that during an oil change on our 2012 Honda CR-V the threads in the aluminum oil pan had stripped due to electrolysis with the steel drain plug, and that our oil pan would need to be replaced for $1,100. However, everything I have checked online and with another mechanic indicates this is nonsense, that the only way this can occur is because of overtightening. Can electrolysis between the plug and pan actually destroy the oil pan threads?
The threads got wasted because someone over tightened the plug. There should be plenty of oil residue on the pan threads to prevent any damage. I am sure you get oil changes atleast a couple times a year, that's not enough time for the threads to get messed up due to a galvanic reaction..
There are repair plugs available to cut new threads, I would go that route.
 
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Thought thats what the sump plug washer or gasket is supposed to assist with? My 28 year old ford uses a nylon washer from ford and never had electrolysis with it
 
Thought thats what the sump plug washer or gasket is supposed to assist with? My 28 year old ford uses a nylon washer from ford and never had electrolysis with it

how? the threads man, the threads.

But yes the gasket seals the threads from stuff getting in
(like salt) and there's oil between threads and inside.

galvanic corrosion not an issue
 
Technically, galvanic corrosion is possible between dissimilar metals. But in the case of an oil drain plug on a vehicle that is serviced regularly and properly, this corrosion is very highly unlikely. Someone screwed up.
 
Aluminum Honda oil pans tend to wear out over time, especially if the drain plug washer isn't changed and the plug gets overtightened (to compensate).

Not always a fault of the shop, but just how those pans are. You can timesert the pan, but a new pan is often the same price. K24 oil pans are kind of a pain to change though, depending on the year.
 
Helicoil is your solution.
Doesn’t a helicoil need a blind hole to bottom out the insert? I reviewed this when I had my issue mentioned above. The only way it would stay is to use thread locker which is a messy situation in an oil pan.

Just my $0.02
 
I cringe every time I try to remove a steel bolt from an aluminum component after it has been bathed in northern road salt because the threads likely to break off of the aluminum. In this case, I’ve never had a problem removing a steel plug from an aluminum oil pan. The oil prevents corrosion. I always use a drop of blue lock tite on any fasteners that thread into aluminum to seal the threads. All that said, the drain plug was stripped by the guy that changed the oil.
 
how? the threads man, the threads.

But yes the gasket seals the threads from stuff getting in
(like salt) and there's oil between threads and inside.

galvanic corrosion not an issue
threads got oil all over them doubt they gonna get stuck??
 
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