1998 V70 T5, 110K. Found a bit of antifreeze is seeping from the thermostat housing. I'm right on interval to about to flush the cooling system, so I figure I lucked out - I'll get a seal and replace it while I'm flushing. Also, the thermostat is perfectly functional and was replaced at the proper interval (75K service), but I figure the part is less than $10 and I'm going to be in there anyway, so I may as well put a new one in.

I seem to remember that an 87* stat was standard in 1998. However, when I called the dealer to see what they had, I was told that 90* was it. They didn't know the brand, only that "it's in a blue Volvo box." (gee, thanks)

Already placing an order with eEuroparts, I picked up an 87* Vernet thermostat. It was either that or the 90* Whaler (OEM?) version. Since the turbo runs a little hotter, I figure I may was well go for the slightly cooler
thermostat.

Does anyone else have experience or insight on this, or any good or bad experience with the Vernet stat? Does Whaler make the Volvo OEM part? Is there really going to be that much of a performance difference between the 87* Vernet and the 90* Whaler? Any and all insight is appreciated.

If you're going to replace the thermostat, get the 87degree vernet and not the 90 mahler. The dealer only sells the 90, like you say, but you'll be much happier with the lower temp one, especially in the winter without any real noticable difference in the summer. Now, in regards to your leak around the thermostat housing. I thought I had one too but it turned out to be the hose from the expansion tank down to the thermostat housing. The over-flow hose, if not sealing correctly will make it look like the thermostat housing has a leak. I replaced mine with silicone hose (to match my vacuum hoses) as www.stylinmotors.com sells a kit for our cars. Looks nice and no more leak! Also, there is no seal on the housing surface where the housing top and bottom meet. The thermostat gasket helps it seal along with the 2 40T torx screws.
Regards,
MIJ
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1998 S70 T5 Emarald Green Metallic, 2004 V70 2.5T Ruby Red, Previous Owner of Black '94 850 Turbo Wagon. My cars have been running so well lately they've got me worried.