Has this roof got any life left

esbliss,

The type of coating depends on the material the existing roof is made from. As your local RV place to tell you what it is if you do not know.

Once you know, go to Home Depot or similar and ask what product works best on the material you have.

Which one is the best?

If it's the black showing through but it's still in good shape, you just need to apply a coating to protect it.

It is rubber, very slick, and very hot to touch. I don't know how to put up photo. I have cleaned the roof really well with a bleach mixture. I am just trying to stop my cash bleeding. If I need a new roof I will get one but really cannot afford a new sheet of rubber.

Is the black you see the rubber underneath or just the dirty mildew stuff that grows on the top of it?
The latter has no effect on life.

My experience has been. The black part can be very slick and if it rubs off so will the coating. Stiff brush it till black residue stops coming off and it might stick better (dicor liq coating and etching agent)

Without pictures, it's hard to say but probably can get another 5-7yrs by coating.

After a couple times coating, it doesn't work as well and it starts to go down into the lower layers of the membrane...eventually, it just doesn't hold up as well.

Some will tell you to replace the roof. I disagree.

Last year I restored the original rubber roof on our 96 Southwind. It had black showing and a couple holes.

I cleaned the roof well, applied Eternabond to the holes, edges and seams.
Then I coated the roof with Heng's Rubber Roof Coating, two light coats.
The roof looks good and is leak free.

I would consider restoring the roof before replacing. Especially, if you can do the work yourself. You will save a LOT of money.