So, my one if my forks (left to be precise) started leaking quite abit if black oil, it started running down the fork and got my fork cover soaked, I've litterly just cut the cover off and all this black jelly stuff was under the cover, I didn't look nice! Anyone know what this black jelly stuff is? Also my fork seal hasn't popped out so why is my fork leaking oil where the fork seal is?

Fork seals don't have to pop out to leak. If the fork tubes aren't covered with gaiters, even bugs that get on your forks can get in there and break the seal. Sounds like you might have motor oil in the forks (black oil). The jelly stuff may be old oil? Maybe the forks just need a rebuild with new seals and oil? I'm sure someone else who knows more will be along to help.

fork seals don't pop, in fact they are a real bitch to get out. They leak because there is a minute erosion between the rubber and the stanchion along with pressure from the compressed forks, forces oil past the seals.

with all that gunge, its def due for renewal.

Pretty much as Lady Sacha says, mate!

With some bikes (possibly all), the oil can 'go off', in the same way old milk does. Don't understand it myself, but there ya go. That's what service intervals are all about.

Depending what the gaiters are made of (don't have such things myself), possibly whatever fluid was in your forks corroded them, or they baked in the heat.

Also, with some bikes you *can* use motor oil in the forks (I have it in mine). Has to be new oil though, so no particulates can fuck up your seals. Also, it's best to read up on what kind and weight work best for your bike.

Unfortunately I've never known my forks to be serviced, but I will get them done as Its all free for me, so can you get special oil for forks? It's a shame because my bikes going to be out of action and my 6 weeks summer holiday is coming up! So no riding for me!

Most people use actual fork oil. Your manual will explain which is required.

Changing the oil in both forks will take perhaps 2 hours at a leisurely pace. This assumes you have the right tools/bike supports, new oil and fresh seals all ready to go.

I don't have an original manual, I've got a 2002 Dt 125 R, any ideas? Can forks be serviced while they are still on the bike? I won't be doing the service as I do not have a clue! I only know how to ride them!

Nope Billy they will have to come off to change the seals. Best to use fork oil of the correct weight for opt performance.

No idea what the black jelly is, possibly old oil that's emulsified, but that usually looks like this:

Here's the oil being poured out for comparison:

... and here's what the seal looked like (note that this one came out easily, the damage you see was there in the fork tube itself):

(guess which one's the old one)

As for oil - nowadays I use specific fork oil, but I have used ATF (Automatic Transmission Fluid) in the past, some people swear by it and some bike manufacturers actually spec it for use in the forks. Just bear in mind you shouldn't need too heavy an oil for the dtr, 5 or 10W would be my guess, if you go for 'proper' fork oil.

Ok thanks guys! Anyone know where I can get gaiters for my DT?

Since it hasn't been mentioned, check your stanchions if they have pits in them new seals will not make any difference. The thick black stuff dont no unless some used crude oil.

You could use a mx fork seal cleaner, very thin piece of plastic wit a hook shape on one end, you push it between the forkseal an fork leg an move it round an it collects and dirt or grit an pulls it out, then there as good as new!

You can make your own with a phone screen protector, worth a try before you get a fork rebuild!

That the same trick as using a feeler gauge from the old days.

Worked on my dt so its worth ashot for him anyway!

To let you guys know, my DT's foks are now getting serviced, new oil, new seals, new gaiters the lot! Thanks guys!