I think I was one of the first people around here to replace thermostat in my X5 35d.

I don't have the record with me, but it was about 2 years and some 30K to 40K miles ago.

I've noticed most recently that the temperature is starting to get twitchy again: when I commute to work I do notice that there's a certain downhill section along the freeway where the temepreture gets in the low 80s.

The thermostat is slowly degrading just like the old one and I suspect that coming winter time I'll replace it again.

Given that the ones available new appear to be just as bad as the one that was originally fitted (i.e. doesn't seem like nothing has changed) I'll probably not buy an OEM anymore.

I'm not entirely sure who makes it, but looking at pictures it doesn't seem to be Mahle, Febi/Bilstein or Gates.

Notice how in these 2 the center disk is attached differently.

Here's the BMW OEM from down below:



Here's the Gates:



I'll give Gates a try on my next one see if it's any better. The cross reference part number is TH35488G1

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