When not to use synthetic grease on o-rings?

I have a tube of Tri-Flow synthetic grease and I am tempted to use it on all o-rings and gaskets that will be exposed to water. But I'd like to know, is there ever a kind of water seal that I should not use it on? For example my underwater pool light gasket does not specify any grease. But what if I put some on, will it help make it last longer before it starts to leak?
http://www.triflowlubricants.com/Synthetic/synthetic.html
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

They state: This pure synthetic grease is fully compatible with most rubbers and plastics.
Key word is "most". I'd guess it will not bother the O ring but I cannot guarantee that either. It may not make it last any longer, but may help it come apart easier later.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Does grease help to fill the microscopic gaps that might occur when the o-ring is pressed against the metal, thus reducing the chance that water can seep through these irregular areas, or is the purpose of grease on o-rings exclusively to stop them from sticking over time?
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

If you need more work to do, please come to my house, and we'll find some easily.
I would not disturb a seal that isn't leaking to put on a sealant.
I think the light you mention won't leak as long as it isnt' disturbed, which you shouldn't have to do until the bulb burns out. At that time, if you put the old seal back so the non-squeezed parts are in the same place, it will probably still last for years, but if you want to put on some sealer then, that might help.
Even though they tell you to replace some seals every time you change a lot of things, I've replaced sparkplugs without replacing that ring (which I can't get off anyhow) and head gaskets on lawnmowers, and quite a few other things still using the old seal without ever having a leak. Of course I look at it to make sure it hasn't been damaged.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
mm - the previous seal was leaking.
The Amerilite pool light was half-filled with water, causing the light to burn out.
The old o-ring was nice and tight, it was just old and weathered.
So I want to make it more reliable if any way possible, not looking for extra work to do.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

They tell you to buy a new seal when you open an underwater light for any reason.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
It was never opened, just old and water leaked in - the bulb was still good before it got wet.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

He's saying it will be opended by the time you replace the bulb, so you should get a new seal rather than rely on grease. I'm sure that's better, depending on how hard it is to find the right seal and how much a third lightbulb woudl cost. For one thing, this seal is under water pressure, which is alot more than if it were in the air but subject to rain. A couple millimeters of rainwater sitting on a seal is nowhere near the pressure of 1 foot, 2 feet of water, or however deep your lights are.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Put a protective coating of urethane on the O-ring.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

I like this stuff
http://www.ellsworth.com/display/productdetail.html?productid04&Tab=vendors
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Site Timeline

HomeOwnersHub.com is a website for homeowners and building and maintenance pros. It is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.