I'm trying to remove the oil cooler and there are 2 big bolts holding the oil lines to the engine. I looked at the Mazda Parts PDF and it's only giving me a part # and not the actual size of the bolt. The biggest open wrench that I have is 19mm but the 2 big bolts seem to be around 21mm or 22mm? I can't get a socket to fit into that space to find the size. Before I go out and purchase the open wrench, does anybody know what size bolts these are? I circled them in red. Thank you.

 

23mm

 

I just tried to find the Same Info out!..my 22 mm wrench will not fit,BUT a 22 mm SIX point socket Does!..WTF?..anyhow,in Standard size try a 15/16.It will work also...By the way,the 23 mm wrench?..sets of wrenches usually have a 21,22,then a 24..(another Wtf? Expresssion!)

 

Go to Sears and pick up an individual 23mm.