I've been driving my 2 tank sys for about 3 years now with no problems with the engine. I would describe my car as an experimental vehicle due to the badly rusted condition so it's no huge loss if it is destroyed (also a good excuse for driving around a "rustic" looking vehicle that some look down on).

winter b4 last I got to the point of just running on diesel for about 20 secs b4 changing over to veg, and it ran fine - and in summer I started not even flushing before shutdown (ie like a one tank sys). Then I had problems this year with the lift pump getting gunked up probably caused by that (got another from the wrecker for $20 - old one had broken piston spring). So now I make sure to diesel flush for 30 sec each shutdown.

Now I'm finding I need 4 or 5 min of running in these cold days b4 switching over. I also installed an electrically heated fuel filter to speed up the switch-over, but I think I need a strong direct line heater just before the fuel hits the injection pump to make it run a lot better, and I assume to protect the engine better judging by the above posts. There's one on ebay for $50 and I've got an idea for a simple home-made one..... Hopefully that would heat to the desired temp almost immediately on start up, so could switch over in 30 seconds or so.

OF course it's not nearly as popular in the NE due to problems in winter.

I think if I installed a sys in another car, I might go for a "Clayton's" one-tank system - a 2 tank system and the main tank has veg oil with about a 2 gallon flushing diesel tank, perhaps installed under the hood if it would fit, or in the side of the trunk. You don't need v much diesel at all, I only fill up about less than twice a year. NOw I think about it there'd be a case for putting some pretty concentrated flush in there instead of just diesel, seeing it uses so little.

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1983 300SD with bad undercarriage rust, with old greasecar 2-tank conversion. About 200K miles, just an adolescent but with premature bone disease.