Thermostat gasket question

[a2058]

In the process of refreshing the cooling system parts and have removed the thermostat. I am looking at realoem and they show to assemble this actually without a paper gasket but just with an O-ring. I have always put this together with an O-ring and a paper gasket to go between the housing sandwiching the thermostat in the past... was I doing it wrong here? Is an O-ring all that is required? So thermostat just goes into the recessed area in the housing on the cylinder side right onto the metal, O-ring on top, and then the housing cover goes on that and 4 bolts torqued down? Is that sufficient to seal without the paper gasket between the metal surfaces of the housing and the cover? Thanks !
My car is 6/85 635CSi.

[TimU]

The BMW Repair Manual stipulates a gasket

[e24mpwr]

Here's the RealOEM link for your car (though I assumed auto transmission, I doubt it makes a difference for the thermostat): https://www.realoem.com/bmw/enUS/par...E24-BMW-635CSi

It looks like the right part might be 11531250399 but they've done some funky merging of the parts over time. FPC Euro thinks that's the right PN.
https://www.fcpeuro.com/products/bmw...-11531250399oe

The Vernet t-stat I put in the M635 came with both a gasket and an o-ring



Relevant RealOEM page: https://www.realoem.com/bmw/enUS/sho...diagId=11_0690

[a2058]

Thanks, I saw that realoem page, it says aseembly without gasket... but yes Bentley does say assemble with gasket for some models... I guess I have a paper gasket on hand so I guess I will use that too...

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Oh, I see, by BMW repair manual, the factory manual? If so then with gasket it is then... thanks!