Battery Terminals - to grease or not to grease?

[StanC]

Hi All,

I've just noticed in the Haynes manual for my wife's VW Polo that 'VW specifically prohibit the use of grease on the battery terminals'(!)

I'm a retired engineer and in forty years of motoring/engineering I've never heard of this being imposed anywhere else and, indeed, the VW garage that services the car smears grease on the battery terminals. I've always carefully applied copper grease to the battery terminal posts on all my cars to improve electrical contact between the terminal post and the cable connectors and to prevent corrosion, without any unwanted effects.

Can anyone enlighten me regarding the technical reason(s) why VW prohibit the use of grease on battery terminals, please?

Stan.

[migrator]

No ideas, Stan. I use petroleum jelly (vaseline) on my battery posts.

[pookie]

I've always been a greaser!


Pookie

[cam]

yep i like a bit of spray grease then i dont get covered in it:thumbs_up:

[pdr944]

petroleum jelly has always been recommended for battery terminals.

[GSMGuy]

Not sure of the electrical properties of "grease" but I'm now beginning to wonder if petroleum jelly is conductive or not - I've always used it on battery terminals etc, but maybe coppaslip is better... I feel an experiment coming on...

Mike

[BIGH66]

Hi All,

I've just noticed in the Haynes manual for my wife's VW Polo that 'VW specifically prohibit the use of grease on the battery terminals'(!)

I'm a retired engineer and in forty years of motoring/engineering I've never heard of this being imposed anywhere else and, indeed, the VW garage that services the car smears grease on the battery terminals. I've always carefully applied copper grease to the battery terminal posts on all my cars to improve electrical contact between the terminal post and the cable connectors and to prevent corrosion, without any unwanted effects.

Can anyone enlighten me regarding the technical reason(s) why VW prohibit the use of grease on battery terminals, please?

Stan.

copper grease all the time :thumbs_up:

[Bernard333]

Stan , I am in the same category as you , long time in engineering and now out of it , I worked for a large manufacturing company and sometimes procedures were written by young engineers and managed to get into print without being properly vetted to make sure the writers intention made sense to the person the instruction was aimed at . When VW prohibit the use of grease maybe they should have specified what type because as you know there is everything from stuff you could use as a conductor to stuff which is an insulator and various stuff in between , there is also grease which when mixed with freeing oil will set hard as rock and cause bearings to seize solid so maybe they had something similar in mind but rather than specifying what type of grease shouldnt be used they just exclude everything , I also hate it when you see this type of instruction without them explaining why .

[keithyboy]

Never done either. As and when the battery has to come off I give them a good wire brushing though.

[V70Driver]

I have looked after my neighbours little old Polo and like my car have always greased the battery terminals as it cuts down on short circuit, damp and corrosion resulting in poor delivery of power.
According to my local VW agent, Breeze of Poole, they advise not to grease the battery terminal as this can result in the car catching fire.
That's their explanation not mine.
I have greased the terminals on my V70 and will continue to do so.
V70Driver

[migrator]

Ah well, my car is old and the insurance is fully comp ...

[Clan]

put it another way .. why does anyone grease battery terminals these days ?
Lead doesnt corrode , the standard clamp is ample to create a good connection they dont corrode and batteries havent leaked since the 1970s and volvo dont grease them from the factory despite what it says on the service sheets !

This practice is old from when batteries has poor sealing where the terminals went through the casing sealed with Tar and the acid fumes created the white fur around the positive terminal .. It may be advised in certain manuals and even volvo service sheets , but no valid reason why you should these days .. VW must have had a few accidents to ban it by the seem of it with no detremenatal effects ...

[StanC]

put it another way .. why does anyone grease battery terminals these days ?
Lead doesnt corrode , the standard clamp is ample to create a good connection they dont corrode and batteries havent leaked since the 1970s and volvo dont grease them from the factory despite what it says on the service sheets !

This practice is old from when batteries has poor sealing where the terminals went through the casing sealed with Tar and the acid fumes created the white fur around the positive terminal .. It may be advised in certain manuals and even volvo service sheets , but no valid reason why you should these days .. VW must have had a few accidents to ban it by the seem of it with no detremenatal effects ...

. . . . . I'm not so sure, Clan. Lead can oxidise and the cable connectors are usually some alloy other than lead, so galvanic action does occur between the connectors and the lead post. Moisture and/or dirt getting in and around the terminals can accelerate galvanic corrosion and lead to corrosion deposits forming. This shouldn't be a problem to anyone who keeps their battery clean, but it can happen - and the Haynes manual does acknowledge that corrosion can occur; it advises regular cleaning away of corrosion deposits with a wire brush. A neat, thin film of suitable grease prevents corrosion in the first place.

I can only imagine that VW is concerned about the fire hazard of there being any grease anywhere in the hot engine compartment. For example, they also don't appear to advise greasing the bonnet release mechanism. I suppose that, in theory and depending on the type of grease, it could conceivably reach its flashpoint, but I've never heard of this happening in practice. But we're just guessing and, as Bernard says, I just wish that they would briefly explain their reasons for prohibiting what has been a long-held practice.

As for me, well, copper grease is a high-temperature product with a high flashpoint - I've been using it (sparingly) on my battery terminals for years and I think I'll continue to do so.

Thanks for all the comments, guys . . .

Stan.

[keithyboy]

put it another way .. why does anyone grease battery terminals these days ?
Lead doesnt corrode , the standard clamp is ample to create a good connection they dont corrode and batteries havent leaked since the 1970s and volvo dont grease them from the factory despite what it says on the service sheets !

This practice is old from when batteries has poor sealing where the terminals went through the casing sealed with Tar and the acid fumes created the white fur around the positive terminal .. It may be advised in certain manuals and even volvo service sheets , but no valid reason why you should these days .. VW must have had a few accidents to ban it by the seem of it with no detremenatal effects ...

Makes sense to me bud.

[simonc]

makes sense to me clan, one possible other reason may be when lead and steel are in direct contact and moisture is present galvanic corrosion can take place, keep the moisture out and you prevent the chemical process from starting, i use ms4 silcone grease

[jco]

Vaseline man myself
I daresay VW would advise against copper grease on alloys to stop them corroding on as well on the grounds that it can get onto the brake discs but I will continue to do that also - as with all things I think its a case of moderation - a smear is one thing a handful is another!