It's not an issue when you have the revs up, but rather only below 12-1500 rpm. Keep in mind I'm talking about an issue that only becomes prevalent at temps around -25*C and colder.

Last time I crossed Canada by car, it was -46, and the heat in my pickup died.... don't want to take any chances ;)

FWIW, I used these parts on my install:

BMW E53 X5 M54 3.0L Engine Drive Belts ES#517967 Hydraulic Alternator Belt Tensioner Conversion Kit - 11287838797

BMW E53 X5 M54 3.0L Engine Drive Belts ES#259467 Idler Pulley - 11287841228

BMW E53 X5 M54 3.0L Engine Drive Belts ES#14608 Idler Pulley Securing Bolt - 07119904677

BMW E53 X5 M54 3.0L Engine Drive Belts ES#21662 Protection Cap - 11281730349

BMW E53 X5 M54 3.0L Engine Drive Belts ES#205356 Mechanical A/C Belt Tensioner Assembly - 11287512758

http://www.ecstuning.com/BMW-E53-X5-...Belts/ES10333/

http://www.ecstuning.com/BMW-E53-X5-...Belts/ES10334/

The Genuine BMW belts are made by continental so I didn't have a problem using the Contitech belts in place of it, to save a few bucks. The whole tensioners/belts/pulleys replacement was done over a year ago on my X and not a single issue. For what its worth, I already had a hydraulic tensioner kit installed on my X but I bought the "conversion kit" from ECS because I like how they package new hardware with it.

Pay close attention to the part numbers on the A/C tensioners. Despite ecs listing 5 different units across 2 different styles (part numbers), only one will work on your X. Verify which one you have before ordering! :thumbup:

Hmm... how do I tell without taking it off? Sorry, bit of a newb here, most I ever did to a car before was change a thermostat:P

Have any of you in Canada ever used www.autopartsway.ca?
ECS has a good reputation, but I'll have to pay big customs duties.

I'm not sure why they show 2 different styles. I just looked at what mine had before I ordered. Check realoem with your vin...

I use ECS for all my parts. The border is about an hour away for me, so I just ship them up to a parcel service and hop across to grab them. Even after duties and exchange it's still a significant savings compared to what I would get them for locally.

I can't cross the border. :(

Let the shipper know you're going to broker the parts yourself. Ups will bring them across the border, but hold them in a bonded warehouse until you take the paper work to customs and clear the items. The carriers don't like it because they can't charge you their outrageous brokerage fees...and they try to be difficult about it sometimes, but it's perfectly legal. Should still save you a ton of cash for getting parts from south of the border without having to cross it.

I'll just buy the parts from inside Canada. My last experience with Canadian customs was such that I won't go near the border ever again, unless I'm leaving for good.