E30 Zone

There's a number of antifreeze options available. What type is best for a 325i. Thanks in advance.

I run modern pink stuff (5-year) in mine with no problems.
I made sure i flushed all the old blue 3-year stuff out properly first.

Agreed. I personally don't think it would make much odds which one you use, just as long as you don't mix them up.

just buy the BMW stuff

The BMW E30 Bentley's manual recommends (in summary) :
Use only BMW approved phosphate-free anti-freeze .
Usign phosphates can harm the cooling system (and may void arranty).

I would personally steer clear of OAT antifreeze and stick with the blue stuff. I did use the pink stuff some 12 years ago but the next 5 years that it stayed there I could smell inside the car when the heater was used a slight whiff of antifreeze. When I went back to blue stuff the smell disappeared!

A couple of years later I suffered water mixing into oil and turned out to be head gasket. The head was found to be ok during pressure testing. I have an M10 engine which generally should not have head gasket issue.

Last month I had a cam belt changed on an E36 with m40 at a BMW dealer and the dealer used the blue stuff for antifreeze. So I would go by what BMW use to avoid possible future issues.

I used Fuchs Fricofin Esk, its phosphate free and the correct blue which bmw recommends

Yes I definitely agree with not using oat and sticking with the blue. I used the oat in my E36 compact and couldn't make out why I kept getting a leak from the seal on the elbow at the back of the cylinder head,turns out that it is not kind to certain types of seals which I found out after searching the internet. I always use triple qx blue for both my E30 & E36. Don't have any more problems.