Joseph Baz replied:

Garry the main concern with plastic cans is static
allways make sure the can is earth when refuelling,allways take it out of the frame or carrier and place it on the ground,as far as durability i have a couple since 1985 with no problems
Rgs,Joe

Simon Evans replied:

Garry,
We have 2 plastic 22 litre jerry cans. Dont know what make they are but we bought them from KMart. We find them a fairly snug fit in the jerry can holder on our camper trailer when they are empty. But when they are full, they expand a bit with the weight of the contents and are a bit of an effort to lift out of the carrier. But I dont know whether 20 litre ones would be any looser.
Simon

Brian replied:

Garry, I sometimes carry up to five 20/22L black plastic containers, purchased from Bunnings (WA) and have had no problems. The comments from Joseph regards static electricity are valid, but they apply equally to vehicles and any other type of fuel container. My main concern with plastic containers has been with chafing, and I solved this by putting pieces of carpet offcuts between containers or their surrounds.