My 2011 35d thermostat observations

[josiahg52]

I was reading Stephen's (sgrice) thread concerning his 35d thermostat woes and correction and it got me thinking about my 2011 35d.

I notice on longer trips that the heat will get a little cool. If I go into iDrive and turn up the fresh air setting up one or two points from center, the heat will be fine. I don't drive my M5 much in cold weather like I have been in the X5 lately so I can't directly compare but I think this is similar to what I sometimes have experienced in the M5. I don't think this is a problem.

Since I got the BMWhat and Torque applications I have been able to easily view coolant temperatures. What I see is that on the highway down to about 2C, coolant temperature fluctuates between 85 and 86C.

At the temperatures that I have been driving in the past couple of days, -5C and down to -10C or even lower, coolant temperature fluctuates between 79 and 81C but I have not had an extended run at these temperatures; only about six miles highway and two miles stop and go every morning and night. Tonight, idling in -11C, I saw coolant temperature lower to 65C.

Fuel mileage is still good I think. As of late, 31+ MPG on the highway and 22+ in daily driving, approximately six miles highway and two miles stop and go every morning and night. I'm sure my drive cycle is enough to fully heat up the engine. If work wasn't so crazy I'd take it on a good long trip and see what it gets up to in this cold weather.

I can't believe that this vehicle may also have a thermostat issue, not that they last forever but I've had enough trouble with the M5s thermostat to last me a lifetime. The new OE thermostat I put in the M5 this past March was running cool when I put the car away in October. I hope I can get this one in the X5 licked. Thanks to Stephen's thread, we now know that the thermostat is marked "88C."