Aluminum block engine?
Should I try to soak a penetrating oil to wick down into the spark plug threads before removing them?
What oil?
Remove the sparkplugs when engine is hot, warm or cool?
Suggestions?
Thank you.
Remove them cold. As long as you are not in an area that is known for rust you should be fine. Try removing them first, I would almost guarantee they come right out.
The title sounds more like bragging. I assume you just got it this way. You have to take a chance, probably cold is better.
Thank you, both.
(238K. What’s to brag about?)
Should I also try a penetrating oil?
I have a coworker with a 2007 civic, with 280k miles on it, he replaced the original plugs at 200k, they came right out. He pulled at least one of them at 100k to look at it and it came out at 100k just fine and they came out at 200k just fine.
I wouldn’t think penetrant would hurt but I bet they will come right out. Remember the engine wasn’t running for all 238k miles so how many miles does the engine really have on it. I wish there would he an hour/odometer that tracked actual engine time running vs straight electric.
I agree with above, The gas engine probably has half the miles which is not much.
For comparison, on my 2005 Camry, the manual says to change to plugs at 120K miles or 10 years. I changed them at 100K miles/~8.5 yrs and they came out just fine. Yours might be very close to mine considering the hybrid part and the 2009 model.
I’ve never understood how a spark plug seal that holds against 1000+psi during a combustion event could possibly allow liquid penetrant to get past it to the threads.
Besides the penetrating oil, and making sure to do this w/the engine cold, folks here have said that if a spark plug is stubborn to remove, try tightening it a little first. There’s one downside with the penetrating oil, appears to me anyway. If you use too much it may tend to wash debris into the cylinder as the plug comes out. Probably good idea to try to clean that area out – while the plug is in – with some combo of shop vac/air gun before putting the penetrating oil in.
@RobertGift
I’ll go a little off topic . . .
May I ask WHY you still have the original plugs at 238K . . . ?1
You’ve mentioned this car before, so I know you didn’t just get it
Do yourself a favor, and install the exact plugs listed in the owner’s manual. Don’t let the parts store guys talk you into something “equivalent”
@insightful
A few days ago, I changed out a set of mile long plugs on a 2008 Ford F450. The 3 valve engine, the one where the plugs often break during removal
I sprayed lubricant near the end of my shift. So it had more than a 1/2 day to soak in
When I removed the plugs the next morning, the threads and the electrode were wet. So I know the lubricant did its job
I’m not losing brain cells trying to figure out why it worked. I just know it did, and that’s the most important thing for me
@db4690
I’d say the lubricant went nowhere until you broke the seal, then quickly went in to lube the threads and electrode.
@insightful
I have nothing to base this on, but I tend to disagree with you
The reason is that the plugs came out very easily
Bottom line, we can agree to disagree
We’re not going to change each other’s minds . . . I’m smart enough to realize that
insightful "I’ve never understood how a spark plug seal that holds against 1000+psi during a combustion event could possibly allow liquid penetrant to get past it to the threads."
In a cylinder, the pressure is brought up rapidly and only has to be maintained for a split second. If the engine is stopped, and one cylinder happens to be a TDC, that pressure would leak down in pretty short order, I’d think. At least, when removing a plug I’ve never heard a “Sssssssssss…” 
The reason this works is because the threads do not make 100% contact there is a small gap that the fluid can seep through. This gap is not large enough to allow combustion gasses out buy will allow fluid to seep in.
Google a cross section of thread engagement and you will see how this is possible.
“The reason this works is because the threads do not make 100% contact there is a small gap that the fluid can seep through.”
BUT, the seal is above the threads. Also, compression can easily leak down through the piston rings. ;-]
insightful "BUT, the seal is above the threads. Also, compression can easily leak down through the piston rings."
True, the rings will easily leak down the compression, but I’d be willing to bet a lot of money (yours) that fluid can get past that seal, either around the top or the bottom of the seal, to the threads. Since you are going against conventional wisdom here, it’s incumbent on you to devise an experiment to obtain definitive proof. I would do it but I’m too busy trying to get my cars to run.
Report back when you have the results.
Autolite’spark plug removal procedure for Ford 3 valve modular engines.
High pressure combustion gases have only a few milliseconds each cycle to seep up through the threads.
Some surely do go out that way, but it’s insignificant.
Penetrating oil has several minutes or more to work its way in, aided by capillary action.
Key from the video: Break plugs 1/8 turn loose before adding penetrant. This makes perfect sense.
I agree that it’s “conventional wisdom” to add penetrant before breaking the plug loose, so there should be a lot of testing and proof out there. I’m waiting.
I got my plugs out without breaking them
And many guys that don’t spray penetrating oil the night before wind up breaking a a lot of the plugs, making the job that much harder
I’m lucky . . . but I’m not THAT lucky
Respectfully, I think spraying penetrant the night before DID make a big difference
I guess I can’t blame you for being skeptical
After all, I’m not sold on the idea that over 50% of the body on frame pickup trucks with a bed sold in the US are 4x4. Despite the fact that some information was presented to me, that was supposed to put the nail in the coffin, so to speak
If you don’t know what conversation I’m referring to, I don’t really feel like getting into it again
I’m just using that as an example
LOL