- A brushing engine enamel at about 80% solids that levels itself as it dries. The finish is the reason to buy it.
- Rated to 300°F, about 150°C. Watch the units: Hycote's 300 is Celsius.
- A pint usually does a whole engine, which POR-15 says in writing and nobody else does.
- Four to six days before the engine runs. Slow by design.
- On bare or rusted metal POR-15 wants its Rust Preventive Coating underneath first.
What it is
POR-15's Engine Enamel is a gloss, brushable, self-levelling enamel sold in US pints and built around American engines: the colour chart is Chevy Orange, Pontiac Blue, Olds Gold, Hi-Po Yellow and the rest, with a few European shades such as MG Maroon and Austin Healey Green. POR-15 does not say what the resin is. It says what it is for: blocks, heads and covers, with anything hotter sent to High Temp.
It reaches the UK through Frost, which is the single route the brand page describes, and Amazon UK lists it under Frost's name. Three listings are reviewed here: black, MG Maroon and Austin Healey Green. The others appear as Frost brings them in.
The figures, and what they mean
POR-15 says the enamel holds its colour up to 300°F. That is Fahrenheit, about 149°C, and the same three digits as Hycote's 300°C, a hundred and fifty degrees apart. It is the lowest rating of the brushing enamels reviewed here, with only Hycote's gloss black at 140°C beneath it, and it is still comfortably above what a block or a rocker cover reaches on a road car. The engine enamel page sets the makers' figures side by side.
The figure that matters more is the coverage. POR-15's kit instructions say the enamel is about 80% solids and 20% solvent, which is why it stays put and dries slowly, and the product page says a pint usually does a whole engine. No aerosol maker says anything like it.
Putting it on
Two cases, by POR-15's directions. Sound old paint is roughened with 320 grit or a scuff pad. Bare or rusted metal gets POR-15's Cleaner Degreaser, then Metal Prep kept wet for 15 to 20 minutes and rinsed, then its Rust Preventive Coating as the prime coat, two thin coats, the second while the first is dry but still slightly tacky. The degreaser is caustic and the Metal Prep step is what puts the surface right afterwards; the preparation guide explains why skipping it costs the job.
Then the enamel. Stir it, don't shake it. It usually brushes without thinning, from the top of the engine down so that runs get picked up as you go, and the brush marks flow out as it dries. The second coat goes on when the first is dry with no drag under a finger, within 24 hours. For a gun, up to 5% of POR-15's own reducer through an HVLP set-up; the spray gun guide says what that needs.
The cure
Touch dry in two to six hours, longer in cold or dry air, because the prime coat under it cures with moisture and the enamel over it is slow by design. Then four to six days before the engine runs: POR-15 is the most explicit of any maker on this, and the application guide draws the wait beside the others'.
There is no heat cure. The film hardens in air, and the engine's warmth finishes it. Parts can be bolted on once it is handleable, gently.
Where it sits against the others
Against VHT Engine Enamel: VHT has nearly twice the rating, an aerosol, and a cure of 20 minutes at 93°C; POR-15 has the finish, the coverage figure and the marque colours. Against Frost's P800 tins: the same job in the same format, with Frost's RAL numbers against POR-15's self-levelling, and Frost 20°C higher on the rating. Against Eastwood's Ceramic: Eastwood has 343°C and a quart; POR-15 has the finish.
Best brush-on engine enamels 2026 ranks it first; it is third overall in Best engine paints 2026.
Who it suits
An MGA, an MGB to 1971 or a big Healey, where the reference names its maroon or its green. Anyone painting a block on a stand who wants the most even finish a brush can give. Anyone who already uses POR-15's rust system and wants an enamel the maker says will go over it.
Not a car that has to run this weekend. And not an alloy head or an engine that is worked hard, where 150°C runs out.