Hmm, I hadn't thought about alcohol content. In theory, at least,that could damage/degrade the seals in old stoves. Though I suspect (with minimal evidence) the current levels are not an immediate hazard.

Perhaps it would be better to get a multi-fuel stove that can handle car gas, and feed Coleman fuel to the Svea?

EDIT: thanks, Mike, this is new to me. I need to check up on my old MSR XGK, which has been my backup stove for a long time. I think Colemans would be especially vulnerable to gunk because of the generator tube they use.