Well I searched the web before posting this question. I found out on one web site of Apple repair service provider that the official thermal paste manufacturer for Macs is MicroSi. But this info is only on 1 site in entire web.
I brought my MacBook Pro to authorized Apple service provider and it provides a paid service that includes replacing old thermal interface with new one. And because I still have AppleCare active on my device I can't get it to another unauthorized service provider, and other authorized ones don't offer such service. There are plenty of such services that are unauthorized by Apple with good thermal pastes, but the key word is unauthorized.
That's why I need to know exactly what paste they use.
Well it seems that the only possible way to get the answer is to ask engineer about it and hope he will give me an answer because they usually don't share such information.