The QB80 has overheating cutout, although mine has never kicked in. Circulating the biodiesel for an hour during mixing doesn't seem too put much strain on it. It's a cheap quality pump (you can pick them up for ~$60 on Ebay) so don't expect too much but they are fine for the job.

I have 2 that have lasted well for 2 years, one of which required a seal replacing due to a leak, but has been fine since.

You could get something more expensive and better quality, but IMHO it's not worth it.

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Sean