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My father (an engineer, but not an auto mechanic) taught me to use a tiny dab of machine grease on the thread (not the rim) of each wheel bolt. This would help against corrosion, and help when loosening the bolt. We've traditionally always switched summer/winter wheels ourselves, on the premise of time and money saved for a simple operation. (Yes, we do use a torque wrench and check the bolts after 100km.)

Online and offline, there seems to be a great deal of argument whether or not to lubricate wheel bolt threads... has this site been able to find a canonical answer? I searched through the tagged questions but didn't find it even mentioned.

If I want to make an informed decision myself, what sorts of pro or contra arguments should I consider?

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up vote 4 down vote

Do exactly what the manufacturer of the vehicle states in service information. Why do I say this? The nut rotational friction and bolt clamping force are both affected by the choice of lubricant used or lack thereof. Almost all OEM's specify no lube. This is done for several reasons. Dry results in the most thread rotational friction, a most desirable attribute, this significantly reduces the chances of the lugs backing off and the wheel coming off.

The biggest concern is a wheel coming off at high speed. This is a highly dangerous event because the wheel accelerates ahead of the vehicle as it comes off at great speed and can and has caused deaths.

Of slightly less importance, but still relevant, is that lubricated threads create a higher clamping force for a given torque than specified. This can stretch the studs or bolts, warp the hub flange and/or brake rotor.

I am an Mechanical Engineer and work in the vehicle repair industry. This topic has been a topic of some debate on professional industry forums. Much to the concern of the informed on said forums is that a significant portion of professional technicians refuse to heed the OEM specifications for both lubricants and torque specifications.

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Great specific answer. Well written +1 – Pᴀᴜʟsᴛᴇʀ2 5 hours ago
    
Except that (I swear I didn't want to open this worm can) wheels won't "come off at high speed" if the clamping force is greater than OEM intentions due to lubricated threads. And it's NOT less importance, it's the absolute crux of it: For head bolts, follow OEM (or aftermarket stud) procedure. For lug nuts, judge the environment and act prudently. Yes, OEM specifies "dry" but they also most likely specify "CLEAN and dry", which is rarely the case. Ultimately, I just would LOVE to dispel the fantasy that greased threads loosen and "back off". Clamping force ends up higher if anything. – SteveRacer 2 hours ago
    
I used to own a '67 Dodge Dart GT that had left-handed thread lugnuts on one side of the car, based on a paranoia that rotational "devil-wheels-gonna-falloff" forces could be countered going forward by changing thespiral of threads. Generating your ultimate torque with thread galling is absolute folly. Clamping force is what maintains torque. not thread grease. I do agree if the OEM is "clean and dry", then use "clean and dry" since they already did their homework. – SteveRacer 2 hours ago

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