Move it between machines
Magnetic Heaters for Generators & Small Engines
A removable way to warm cold oil in generators, snowblowers and other equipment—when there is enough exposed steel to use one safely.
The short answer
Most useful on larger steel-sump equipment. Compact air-cooled engines often have aluminum crankcases, where a small thermostatic adhesive pad is the more dependable choice.
Check before buying
Find the oil-holding part of the engine and test it directly with a magnet. Do not assume a steel frame or shroud will transfer useful heat into the oil.
A simple four-step setup
Check the engine manual for heating restrictions.
Confirm the oil sump itself is magnetic.
Attach before an expected storm or cold start.
Remove it before starting or moving the equipment.
Good fit
- ✓ Diesel generators with steel sumps
- ✓ Older snowblowers and shop equipment
- ✓ One heater shared among machines
- ✓ Emergency preheating before forecast outages
Choose something else when…
- — The crankcase is aluminum
- — Fuel or vapour can contact the heater
- — The machine is enclosed without clearance
- — The manufacturer requires a cold-weather kit
What size should you buy?
Rule of thumb: Use the smallest suitable heater; small oil volumes need gentle heat.
Best placement: Directly on a flat steel oil sump or crankcase surface, with open space around the heater and cord.
Magnetic heaters to compare
Start with the 200 W model for cars and small engines. Move up only when the equipment and heater manufacturer support the larger size.
Amazon buying options
Zerostart 3400017 magnetic heater, 200 W
A magnetic surface heater from Zerostart. Grips any flat steel surface — oil pan, transmission pan, small-engine sump. CSA certified.
Match the surface material, size and manufacturer limits. This is not vehicle-specific fitment.
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Amazon buying options
Zerostart 3400021 magnetic heater, 300 W with thermostat
The bigger magnet heater for trucks and tractors, with a built-in thermostat that cycles the element instead of running flat-out all night.
Match the surface material, size and manufacturer limits. This is not vehicle-specific fitment.
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Quick questions
Can I put one on a portable generator?
Possibly, but many portable generators have aluminum crankcases and very little flat space. Test first. A 25–50 W adhesive pad is often easier to size for their small oil capacity.
Can it stay attached while the generator runs?
Treat a portable magnetic heater as preheat equipment: unplug and remove it before starting unless its manufacturer explicitly approves operation in place.
Vehicles with a permanent heater already catalogued
A magnet is the fallback. If your engine has a frost plug, the fitment page lists the element and cordset that belong in it.
Need the full comparison? Read the magnetic block heater buying guide or use the heater selector.