Donnymac

Assuming there ere no system leaks, water in your motor will not boil at 212 but probably 220 or higher.

first reason is the system operates under pressure which raises boiling point and motor oil temp.....all as designed.

Second reason is antifreeze additive........it, too, raises BP of water.

200 degrees is a very motor safe operating temp.

bkdc

Unfortunately, other parts, and in particular, rubber in gaskets, do not like high temperatures. You can ask BMW owners about the oil leaks they face at 80k miles as the gaskets, which cost 40 dollars, end up with 4 hours of labor time and 1000 dollars at the dealer to replace as the engines run at 245f all day. I just swapped out my wife’s oil filter housing gaskets this weekend. The engineers at BMW have absolutely no care in how the design affects repairability and it’s clear the company does not care how long the car remains problem free past the magic warranty and CPO periods. Forced to take off the intake manifold just to remove one bolt.

With modern oils, running a turbo engine at 200f is just fine. Modern oils will not get too thin under engine temperatures. The engine wear is at the other end with wear during cold starts which is why cold weather drivers are better off using a thinner oil like 5w-30 or 0w-30 to protect at cold starts. There are plenty of MB approved oils at 5w-30 or lighter.

Bigdriver4u

I read this thread a few weeks ago before I changed my oil in my 2014 w222. I went from Mobile 1 5/40 to Motul 8100 5w40 during my A8 service. My temperature before the oil change was running at 200. Post change it's running at 190. Maybe using a truer level 4 synthetic vs Mobile1 which is at level 3 makes a difference.

gregorynp

My 2016 always reads 190-200. The manual says "X Check the coolant temperature display in the instrument cluster.

The coolant temperature must be below 158 ‡ (70 †)."

Whats up?

as.thompson

For what it's worth, my temp after warm up is always 200 degrees.

S_W222

mine always reads 200F when driving, or 190F all the time when idle.

rebounder63

I have a 2016 S550 4Matic with 110,000 miles. Recently I had to add some coolant and I noticed some type of leak at the bottom of the over flow reservoir and hose. I replaced the reservoir and hose, flushed the system
and topped off the system with the OEM red coolant. Car ran at 190 degrees for a day then settled at 200 degrees, which appeared to be the prior normal temp. There are 2 coolant reservoirs independent of each other.
The smaller one is located under the engine's center panel..

JohnLane

The smaller reservoir is for charge air coolant.

My 2015 S-65 runs at 190 except when ambient gets over 100 degrees with stop and go driving... then 200 degrees and it is a bit of a slug due to not getting intake air temps down to ‘safe’ levels for max boost. I’ve never seen higher then 200 even driving in 120 degree heat with A/C keeping the cabin cool. MB did good with sizing of the radiator, condenser and fan. I’ve never heard the radiator fan blow faster than half of what is capable of. That said clearly charge cooling and oil cooling lacks sufficient capacity as charge temps and oil temps go way up in over 100 degrees of ambient with giving it some boot. Can watch oil temps climb when rolling on power.... 230-240 is where I back out and it takes a long time to cool down.