Dead easy to use - just read the instructions. But the piston head must be the right shape - domed ideally and not indented like a V8 piston head.
As I recall you just squeeze the rubbery goo down the spark plug hole and then either leave it or idle the engine but the instructions are very clear. There was something about running it in gently for 50 miles.
As for how long it lasts I don't know as I didn't do many miles anyway and sold the LR shortly afterwards. But certainly OK for six months. I think it's meant to be OK for 5,000 miles or so.
Holts have a tech support line that are helpful as I recall.
Again as I recall the instructions are inside the box so probably best to ask if you can open it up and read them before buying.
Mike
