for $4 I would always replace the Radiator drain plug if I touched it, same with bleeder screw

https://c1552172.ssl.cf0.rackcdn.com/441860_x800.jpg

https://www.ecstuning.com/BMW-E53-X5...ing/ES2681417/

:iagree: Smart man. Additionally, I'm usually replacing the hoses at the same interval as a complete system flush.

2002 X5 3.0 289,600 miles
2004 325i 123,000 miles

^^srmmmm, would you be ok with it if you had a spare radiator drain plug on hand?

Btw what is your time regimen again for cooling system components? I dont do as many miles as you but time on cooling system components to me is just as important as miles.

Me, I replace the Prestone every 4-5y/50K or so.
Just me, don't know about others.

I dont get not opening the block drain.

I've done it a few times with a few different BMW's without any problems.

Any particular reason not to?

I do the complete system, coolant and all hoses every 150,000 miles, which for my E53 is just under every 6 years. On my wife's 2004 325i though which is only seeing about 10,000 miles per year, I stuck with the 7 year interval. I think as with the engine oil and CCV system, my 60+ mile commute each day means fewer thermal cycles on the cooling system as well, so components and fluids tend to perform towards their best efficiency and lifetime levels.

As for the drain plug - if it's not leaking, I'd leave it alone. Besides, I'm still on my original radiator at almost 290,000 miles.

^Good call on the 6 year intervals. I'll look into it in the spring and perhaps get a Stewart pump that will outlast the vehicle.

I only mentioned the radiator drain plug because plastic tends to be brittle and I would feel fine about draining from the radiator if I had a new one on hand (I hate re-using old plastic parts)

^At least you get a hint of that brittle stage when the radiator hose ends start to turn brown. The radiator condition is more difficult to evaluate, but my past experience as a Mazda supplier showed that leaks usually appeared at the header/tank seam before the plastic tanks started to deteriorate.

Unless you forget to like I did last time. Then you feel like an idiot and hopelessly hold on to it thinking that you'll remember next time.

You remember quicker when you forget to put the lower hose back on...And by the way, it can require up to 4 quarts of oil to remember to put the pan drain plug back in. :rolleyes:

2002 X5 3.0 289,600 miles
2004 325i 123,000 miles