I presume this is what they are recommending?
https://www.bgprod.com/catalog/engine/bg-shear-power-hd/#bg-product-7
Not really any decent data on this that I can find.
Their claim:
Shear Power® HD far exceeds all industry standards.
The reality: not one shred of data to back it up on their sight. No testing protocols, not accreditation, no third-party testing, nothing ...
Nothing here:
https://engineoil.api.org/Directory/EolcsSearch
I found this amusing; a direct quote:
Why can’t I buy BG products at a retail outlet?
BG products are professional-use only and require the knowledge of specially trained technicians to perform services.
Apparently I'm simply too stupid to open a bottle of product and introduce it into the crankcase ...
I'm not saying it's bad. I'm just saying it sounds like a pricey lube that will line their pockets far better than it will ever make a difference in your engine. It is
my opinion that they are a marketing program; they offer many products and services, and push only their solution as the best, with no proof to back it up.
Granted, you've told us nothing about your intended use; OCI duration, severity, etc elude us at this point. But I feel comfortable in stating that generally normal products suffice just fine for the VAST majority of uses. An expensive, boutique syn is not needed, and rarely would have any hope of providing a decent ROI.
I don't see them listed as a "don't buy" on the PQIA site; I don't think the product is truly junk. But I seriously doubt they provide any more actual performance than any decent CJ-4 you can get at the local WallyWorld.
Also, you state that your mechanic is recommending extended OCIs. I'm a fan of that, but ONLY when the program is well managed. What are the specifics of the testing, lab, etc that he/she is suggesting? Extended OCIs are not something to play around with; you really need to understand the pros and cons.
Finally, this ...
I presume the Dmax is the engine you're with; from your sig line.
I can tell you from personal experience and (literally) hundreds of UOAs that engine could not care less what you put in the crankcase as long as it's a proper HDEO. Every bit of evidence shows that it does not need any special lube at all; no super syns, no additives, etc. Do not get sucked into the hype!