i've been running the nylon for 6 yrs. never a problem
My first gauge install used nylon and I never had a problem, my last gave me no ends of trouble, and I discovered there are different qualities of 1/8 nylon line.
The one that leaked into my head unit was a relatively thick walled line that was supplied with the Equus gauge set.
|removethispart|@bentparts - I've yet to see an electrical gauge set in the small 1-1/2 inch style - which is the only size that can be neatly fitted into one of the DIN radio slots (50mm - 1.97 in high) - the next size up is 2-1/16 inch, followed by 2-5/8 inch.
If you do know of a manufacturer who makes electrical gauges in the 1-1/2" size, I'd love to hear about it - because I'm in the market for oil pressure & voltmeter.