Apparently more related than you think. My mpg jumped 15% immediately upon replacing thermostat. With the defective t-stat, my fake gauge stood at perfect noon any time the ambient temp was over about 40-50°. When it was zero outside the coolant temp never made it to 140 and that was the only time the "gauge" gave me any useful information.

The cabin temp of 10° was more direct feedback

A working "gauge" works exactly as I described: see the thread here: http://www.bimmerfest.com/forums/sho...d.php?t=854029

This is for the e46, I'm not sure exactly the buffer values for x5 but it's similar.

The coolant temperature "indicator" (most definitely not a gauge) snaps to noon at 75°C and stays stuck at noon until the temp hits 115°C.

167F is not remotely "normal operating temp" and I was told the engine won't kick into closed loop at that temp, the immediate jump of 15% in mpg seems to follow that logic though it could be some other factor of course.

I just know that I drove my e53 many 1000s of miles with coolant temps below 80°C and got terrible mileage. My wife's clone x5 got 23 highway and I got 20-21. Until I replaced the tstat and instantly mine nearly matched hers and I would get 22-23 avg at 75mph.

Not arguing exactly what cause and effect make my mpg horrible but it was 100% the fault of the idiotic temp "indicator" that stays the same for 40°C. (72°F).

It cost me $100s in wasted gas ⛽️ and frozen body during 5-6 trips to/from Chicago when ambient was zero F and I could not warm the cabin above freezing. I had to stop every 20 miles to let the engine warm up enough to get any heat in the cabin and keep the engine running. (At one point the needle pegged high and the elec. fan kicked on: opened the hood and hand on the radiator hose confirmed engine was cool).

Anyhow done with my rant: as soon as possible I will reprogram my temp indicator to have non moronic buffer values like 90-100C.

Cheers.

+1

I think we've done 3 on our 2002 E46.

I've done 2 on my E46 and one on my E53 :pullhair:

Mike

Lubro Moly Pro line engine flush (since I don't know what built up in the engine prior to my ownership 33k miles ago) and another nice OE filter and Rotella T6 oil change, then did my "mid winter cleanup" detail which should almost hold me over till spring.

Hey RB,

thoughts on Rotella T6? I've been using mobil 1 for my oil.
and any steps for mid winter cleanup?

Not RB, but I'll say that I just converted to Shell Rotella T6 after being an AMSOIL (AMO - 100% synthetic 10W-40) user for over 25 years. I run it in all my BMWs and will soon put it in the 4Runner.

I converted to T6 after nearly a full day of researching the specs of the two products. The TBN of the T6 appears to be a little lower than the AMSOIL's 12 in virgin oil analysis reports I have seen, however, I am not driving my vehicles near the 25K miles that the AMSOIL is rated to give (when used with their filters). I am about 8K miles/year on each vehicle. I can change the Mann filters on the BMWs every 6K miles and believe that I can get 12K total miles out of the T6. :dunno: :dunno:

I do like the more modern 5W viscosity of the T6 for my cold weather ops.

The economics in my mind also favor the T6 with a gallon of T6 available at WalMart for ~$22 and 4 quarts of AMSOIL being ~$32, so a delta of about $20 on a typical 8 quart BMW oil change.

Your evaluations for your situation may vary :dunno: :dunno:

Edit: See my E46 posting with oil analysis reports here

E46Fanatics - View Single Post - Shell Rotella T6 - my experience

http://home.earthlink.net/~alan.m.ro...lla5W-40T6.jpg

http://i571.photobucket.com/albums/s...psc61f4548.png

Here are the some of the M1 numbers:

https://mobiloil.com/~/media/amer/us...guide-2016.pdf

and here are some additional virgin oil analyses that I found. Castrol's 5W-50 looks pretty robust in TBN and zinc

http://rennlist.com/forums/attachmen...e_5w-50_sn.jpg

http://rennlist.com/forums/attachmen...5w50_voa_2.jpg

http://rennlist.com/forums/attachmen...il-t6-5w40.jpg

Mike

Love the feedback on the oil. Lumba2 (wife's x5) just lit up oil service a week ago.

Logic makes sense though the forum sampling is extremely small part of the universe of X5s and we hear about those having problems not those that are not.

Took it on a nice snow day. Except 1-2ft in 1 day and bad plowers did not make it easy. (1st pic is mid storm. Last 2 after after)
http://i924.photobucket.com/albums/a...psl1sjn0mz.jpg

Then took a trip to the next town to check on other properties. It was worse XD
http://i924.photobucket.com/albums/a...ps3s7xlfks.jpg
http://i924.photobucket.com/albums/a...ps7gzofzdp.jpg

And there is supposed to be another 1-2 ft this week. We just cleaned what we could and got outa there!

Is that Lake Tahoe?