Koch-Chemie Motorplast "Mp" Engine Preservation 500ml

Preserve the engine bay instead of just sprucing it up for a minute

What is Koch-Chemie Motorplast? A water-based, silicone-free polymer preservation for engines, ancillaries, housings and rubber hoses that forms a permanently elastic protective film up to 250 °C and carries the Daimler factory approval (GOTIS P 00.16 – 02.0). Not suitable for drive belts, brake components, body paint or open intake areas.

Koch-Chemie Motorplast „Mp“ is an engine preserver from Koch-Chemie that protects plastic covers, rubber hoses and ancillaries in the engine bay against corrosion, road salt and UV stress with a permanently elastic polymer film. You spray it on as a pump mist over the pre-cleaned, still-wet engine bay, where it pushes out the residual water and cross-links after 6 to 8 hours into a dirt-repellent, wafer-thin layer. Unlike classic engine-shine sprays, Motorplast skips propellants and silicone, which is what clears it for use in body shops (no painter's fisheyes) and on Mercedes-Maybach models (official factory approval).

The look stays deliberately satin-matt rather than high-gloss — the surface keeps its original character, the protection is physically there without the engine looking like it has just been oiled up. After the treatment the bay looks clean, not „greased“. That's the OEM logic behind the Daimler approval: not gloss cosmetics, but material protection.

• Daimler factory approval instead of marketing shine. Motorplast is listed internally at Mercedes-Benz under GOTIS number P 00.16 – 02.0 and is approved up to Mercedes-Maybach. The approval checks compatibility on EPDM coolant hoses and PA, PP and ABS covers under 90–110 °C sustained load — that's why brand workshops reach for this product instead of any random engine-shine spray.
• Silicone-free and propellant-free. The water-based polymer carrier holds no volatile silicone oils (critical near paintwork — think fisheyes) and no aerosol (no butane/propane propellants). VOC content about 3 %, labelling required under GHS07, but not flammable. That cuts the risk on jobs done right there in the shop considerably.
• 3 to 8 months of protection, 50–200 ml per engine bay. A 500 ml spray bottle lasts for 2 to 10 full treatments depending on engine size, which works out to 1 to 3 years of car care day-to-day. In the 5 L pro canister the price per litre drops noticeably — that version is built for detailing shops, fleet care and high-mileage households. 20 and 200 litre containers exist for industrial customers.

Detailing1's tip from the shop: The most common mistake with Motorplast isn't too little, it's too much. Lay down puddles instead of a fine mist and you stretch the drying time well past the usual 6 to 8 hours, the polymer cures unevenly and leaves milky edges or tacky spots. The clean routine: let the engine cool to hand-warm, pre-clean with Green Star at 1:10, rinse off with a soft water jet, mist Motorplast thinly into the still-wet bay, close the bonnet and let it sit overnight. Tap any leftover pools the next morning with a dry microfibre cloth. It's self-levelling — no working in with a pad needed.

Spray it on wet. Bonnet shut. Dry overnight.

You spray Motorplast onto the pre-cleaned, still-wet engine bay because the residual water carries the polymers right into the tight gaps before the product itself pushes it back out. That's pro technique straight from the Daimler factory-norm test, not a marketing slogan.

Before you apply, let the engine cool down — hand-warm is ideal, boiling hot is not. On a block sitting at 130 °C oil temperature after a motorway run, the water-glycol-ether mix flashes off instantly and burns the polymers into the plastic as streaks. The officially approved heat window is 250 °C component temperature — that's for the cured film, not for the moment you apply it.

For a mid-size car, reckon on 50 to 200 ml. Work sparingly from about 20 cm away with the spray head and go systematically from back to front — valve cover, fuse box, then intake manifold, then the visible hoses and seals. You can reach awkward spots with a Cyclone or Tornador gun at 4 to 6 bar; in the home garage the supplied spray head does the job. Keep the mist away from open intake tracts and mass airflow sensors — those hot-wire sensors react badly to polymer coatings.

Once it's on, close the bonnet and let it sit 6 to 8 hours, ideally overnight. Day-one test: check the next morning whether any pools or drips are still holding. If so, tap them with a dry microfibre cloth — don't rub. The film is self-levelling and needs no mechanical spreading.

Plastic, rubber, ancillaries. Never the drive belt.

Motorplast is approved for the typical engine-bay materials: PA, PP and ABS plastic covers, EPDM rubber hoses, seals and metal ancillaries in aluminium or steel. On these substrates the permanently elastic polymer film forms, holding off dirt build-up by months and slowing road-salt corrosion.

The hard limits are friction- and safety-critical. Drive belts, V-belts and pulleys are off-limits — the polymer layer cuts the grip friction, the belt slips and worst case the alternator drops out. For the same reason, keep it off brake components, brake disc faces and the pedals. On body paint, overspray leaves streaks and is pointless there anyway — Motorplast is no paint sealant. Any mist that lands on an inner wing or bumper edge, wipe it off straight away with a damp microfibre.

If too much product did end up in the bay and milky streaks have formed, a stripping routine with an alkaline cleaner sorts it: spray Green Star on generously at 1:10, foam it up with a soft detailing brush, rinse off. The cross-linked polymers break down under the APC and the film comes off without residue. After that you can lay on a second, thinner coat of Motorplast.

Spring and autumn. Twice a year is plenty.

The typical rhythm for Motorplast is twice a year — once in spring after the salt season and once in autumn before winter sets in. In between, dusting the plastic covers with a microfibre cloth is enough. Detailing shops slot the product into their winter-check packages, because 5 minutes of work buys 6 months of corrosion protection.

The 500 ml spray bottle is the right call for a single car or for hobbyists getting seasonal vehicles like convertibles or classics ready for spring. Per treatment 50 to 100 ml — so the bottle carries you across several seasonal cycles. For multi-car households or commercial detailers the 5 litre canister pays off: noticeably lower price per litre, just decant it into a separate Koch-Chemie cylinder bottle with a spray head. 20 and 200 litre containers are pure industrial variants for workshop groups and OEM supplier chains.

Storage is fussier than with many other detailing products: Motorplast keeps at +5 °C to +25 °C, frost-free and out of the sun. Frost breaks down the polymer emulsion and the product won't spray cleanly afterwards. It's fine in the garage or the stockroom — just don't let it overwinter in the boot.

Apply Motorplast properly once — cold engine bay, wet pre-clean, thin mist, bonnet shut overnight — and you get an engine bay that looks the same after winter as it did before. That's the Detailing1 standard: not shine in the shop window, but an engine that still runs like new after three winters. For full seasonal care you pair Motorplast with Green Star as the pre-cleaner — that's the complete engine-bay workflow in under 30 minutes per car.

Application of Koch-Chemie Motorplast

Pre-cleaning, wet application, overnight drying

Allow the engine to cool until it is only hand-warm — boiling hot leads to streaking. Cover sensitive components such as the alternator, open intake areas, and mass airflow sensors with foil or microfiber.

Liberally spray the engine bay with Green Star in a 1:10 dilution and carefully agitate with a soft detailing brush. After 2 to 3 minutes of dwell time, rinse with a soft jet of water — no direct high-pressure spray from 20 cm distance onto sensors or control units.

Immediately afterward, spray Motorplast into the still wet engine bay. Sparingly, in a very thin layer, from about 20 cm distance. For a mid-range car, you can expect 50 to 100 ml; for V8 blocks or fully built SUVs, up to 200 ml. For hard-to-reach areas, professionals use a Cyclone or Tornador gun at 4 to 6 bar — for a hobby garage, the included spray head is sufficient.

Close the hood and allow the product to set for 6 to 8 hours, ideally overnight. The next day, check if any puddles or drops remain. If so, dab with a dry microfiber cloth — do not rub. The film is self-leveling and does not require mechanical spreading.

Notes: Do not spray on drive belts, V-belts, and pulleys — the polymer layer reduces static friction and can lead to belt slip. Also, avoid brake components, pedals, and car paint. Keep spray mist away from open mass airflow sensors and lambda sensors. In case of overdosing with milky edges, Green Star 1:10 can be used as a stripping solution. Storage is strictly frost-free between +5 and +25 °C, protect from direct sunlight — the polymer emulsion breaks down in frost. Use within 24 months after opening.