Years ago, I used some of the formulator's previous version of the product (MT-10) in a car engine & saw a noticeable decrease in operating temperature. The formulator departed that co & started another with the improved, reformulated SteelShield products. I'm running the words together here so it can be found by the search engine easier.
I,m currently using their SteelShield EPA in a car & truck engine, also in the truck differential & transfer case.
Haven't driven truck enough since to determine much except noticeably longer time to warmup to normal operating temperature--about twice as long. I don't think the cooler running engine is particularly helpful to mpg during winter. But, I've seen no loss of mpg.
I've been running near full recommended dose (6oz of recommended 8 per gallon) in the (Prius C) car engine for last apprx 5500 miles, since 10oct2013. Again, the cooler running engine is not particularly helpful to mpg during winter. However, I have been getting 70+ mpg trips on a regular basis, whereas, before, that was rare.
Per the onboard mpg tracker, year round average has been around 62-65 mpg. Thus far this month, with longer, warmer days, average is just below 75 mpg. By the way, I'm a hypermiler.
I've been unable to disprove any of their claims. I think a couple of their claims is smoothing of the metal surfaces & reduced metallic debris in the oil, with use of SteelShield products. I plan to do some UOA's to see if they confirm the reduced metallic debris claim.