There are two different Evans coolants. There's the regular NPG, which has a viscosity similar to syrup, and the NPG+, that is similar to regular coolant. NPG+ can be used in confidence with no modification to your cooling system, with the possible exception being a change to using a 7Lb. pressure cap.
Check out this link to the details on NPG+:
www.evanscooling.com/html/npgPls.htm
If I gotta keep doin' this, I'm chargin' Jack Evans a commission...
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"We drive into the future using only our rearview mirror."
- Marshall McLuhan -
Scott Longston
Northern California Wine Country...
"Turbos whistle, grapes wine..."