What is the most oil and nitro resistant covering?

I know there are loads of people who seem to be able to put a model together just about every week it seems but I'm one of those for whom the process takes a year or more especially when scratch built. To that end I want my models to last a long time but I also want to fly with Cox engines and the associated mess of oil and sometimes spilled raw fuel containing high levels of nitromethane both of which are known to eventually destroy airframes and covering.

I know this topic has been touched on a lot on this forum already but here I go asking again ...

Since you guys predominantly fly Cox engines I thought I'd ask you what coverings are most resistant long term. I've done a little bit of research by reading build articles from the 1/2a craze in the 1970s. Most of them use monokote or solarfilm with occassional mention of epoxy based finishes. I'd imagine a fully cured epoxy finish to be one of the best especially around the engine compartment whereas the plastic films, I imagine, would tend to lift along seam lines quite soon after getting covered in oil and nitromethane.

What are you using?

I've used Ultracote on two 1/2A planes back in 2011. The first was a Li'l Jumpin Bean that only lasted a couple of years before wearing down to a nub, then being redesigned and resurrected. The other from the same roll of film was my Li'l Satan which I still fly several times a year, often waiting a week to be thoroughly cleaned. The only film that lifted so far on it was the open-ended patch I ironed over the pushrod exit, and it was getting loose after a year so I pulled it off. That was when I was giving it a makeover for the Traveling Tee Dee engine. I have always epoxied the engine area, lately switching to polyurethane for weight savings, smoother application, and so far equal fuel resistance.

Ever since those two builds I have used Monokote on my wings. This is how I do it with no sock or heat gun. With Monokote the glue temp and shrink temp overlap so you just have to get the feel of it, and every roll and color are different. When you get to shrinking temp, you'll see a color change as you pass over an area. Usually, it'll darken as it shrinks, but will return to normal when cooled off.

The seams are critical. I apply it to the bottom panel first, wrapping it around to cover the whole LE and TE, ironing it securely along its length, and then trim it short of touching the tops of the ribs, and also the same way on the TE. Then I cover the top wing panel, overlapping a half to an inch to the underside depending on the size of the plane. Now all the seams are on the bottom of your wing.

Next, I use the iron to make sure it's completely glued down to the entire LE for its whole length. If the wing has fixed flaps, iron it securely to that wood on all sides before shrinking the TE sheeting and rib bays. If you wait till after you've shrunk the rib bays, you'll have trouble getting it to stay adhered to the fixed flaps because it's already too tight.

Now I use an iron to stick the adhesive firmly to the center sheeting all the way around. Any bubbles from gas trapped underneath can be fixed later, but wait until last to do that. Once your center section is ironed securely, turn the heat up and start gradually shrinking the rib bays one at a time. Do it over and under all the way from center to tip, top and bottom, trying not to glue it to the ribs and spars, though it can't be avoided, save that for last. Once all of your bays are shrunk, cook out any stubborn wrinkles, and run the iron over the ribs and spars.

Using a new exacto blade pop the point through ant bubbles over solid wood and shrink and stick them down with the iron. Now when you apply the fillets to the wing roots, make sure the fillet overlaps the Monokote for at least 1/16".

I gotta go now, I can come recheck what I wrote and answer any questions later.
Rusty