Any particular antifreeze for a 221 flathead
 

Time to get my rebuilt truck ready for its first winter since restored. I use the old green antifreeze in most of the farm equipment round the shop. Will that be fine in the flathead. If not what you guys recomend. Thanks.

Re: Any particular antifreeze for a 221 flathead
 

Absolutely will work great. Green is the closest to the original permanent antifreeze back in the day, which gradually replaced alcohol (methanol) based antifreeze. It was called "permanent" because it did not evaporate ('boil') out of the cooling system like methanol, which meant topping off the radiator was a regular chore. Methanol boils at somewhere around 170-180* if I remember. So you changed to 'winter' thermostats (160*) in the fall so the methanol didn't disappear so quickly. Then went back to 180* in the summer. With "permanent" antifreeze you could leave the 180* stats in and get more warmth from the heater.

Re: Any particular antifreeze for a 221 flathead
 

I use Sierra antifreeze, it is proplyene glycol and is safer for animals.

http://www.peakauto.com/products/ant...motive/sierra/

Re: Any particular antifreeze for a 221 flathead
 

Me too, and the insides of my alum heads still look like brand new after 17 years on the road.

Re: Any particular antifreeze for a 221 flathead
 

X2 Sierra. Been using it for 20 years in my Flatheads. Just get the antifreeze tester for it as the regular testers won't work. Cost about $2.