I couldn't tell much difference from the description on the packaging. Black costs more, is it better? Or do they both have strengths in different areas?

I'm sealing up my oil pan. I used black on my intake base, and that worked. I'm lost on this one.

 

Here are my general rules which I am sure people have had different results with.

I only use Blue or Ultra Blue permatex on things that come in contact with coolant. Blue is also useful because it's mostly clear and dries pretty clear, so you can use it on parts that will not see engine fluids, or super high temperatures, but are visible so you don't want it to look like you sealed your part with bathroom caulk.

Black is great IF YOU CAN GET AIR TO IT! I heard for years to use black everywhere. I did an intake one time with it, let it cure for over 40 hours. It leaked. Took it back apart and the inner part of the permatex was just as wet and uncured as when I put it on there. If you use it, for instance, with cork, the cork is permeable and will let it breathe and cure. Black will adhere to surfaces much better than the other types, but if you can't get air to the middle of it, it will never cure.

Silver is all around good. And it's sensor safe. Cures well. I have had a rear intake leak with silver before. Could have been operator error on that one. It holds surfaces well.

Ultra Gold is my favorite. Especially for rear intakes, or other areas that come in contact with oil. It seems to do very well. Once it cures, it does not adhere as hard as black does, but it sticks just fine as long as you prep the surfaces you're working with.

Blue does not have super duper adherant properties, so it's also good on things that you may have to take off down the road and want to have the option of re-using a gasket here or there. Silver black and gold will most certainly destroy gaskets, but they sure seal. Black is the only tricky one because of the difficulty in getting it to cure.

Some people highly recommend Dow Corning construction adhesive for all areas that come in contact with oil. It's silver. Supposedly used on top fuel cars and the like, and if you have ever seen an intake come off an L98 that has never before been apart, the OEM color was silver. No idea what was used there.

I don't know what year your car is, but on the one-peice oil pans, you should need VERY LITTLE permatex anywhere. In the past when I've done cork 4 peice gaskets, I've used either silver or ultra gold.

Why don't you go buy some different kinds and put them on a peice of cardboard and then some aluminum and maybe some cast iron somewhere. See how they cure, how well they hold and how long the middle stays squishy.

 

Use the Right Stuff and throw the rest away. Its by far the best stuff I have ever used. Goes on easy, and never gets brittle, sensor safe, and sets up in about 30min - 1 hr completely. Bonds to about any surface, even polished metal, to the point it needs scraped off. The reason most RTVs fail is because they get hard and brittle. I had some of this stuff fall onto my header collector, it never burned off or even got hard, but I had to feel it off and it was as stretchy as the other stuff I had applied. It just turns into a rubber compound that is flexible. I would bet you could get away without even putting an oil pan gasket on with this stuff. I wouldn't try it, but you probably could. LOL :cheers:


[Modified by ski_dwn_it, 9:42 AM 4/29/2003]

 

I use Red for standard applications and Orange (Copper) for high temp places (like collector gaskets).

 

I added some ultra copper to my collection. BTW, Orange and Copper are two seperate types. I believe there's: Black, Blue, Red, Orange, Copper, the Right stuff, and some other lowly types that come in wussy-sized tubes.

 

I did not realize that, I only call it orange becase it is really orange in color.