Changing oil every 5000 is not a bad rule of thumb. If you're using synthetic, you can go longer. Some are very anal about this. I won't debate the issue. But I, personally, run my synthetic oil 7500 or longer. And I would suggest a quality filter, such as a Hastings, while foregoing a Fram or other such garbage.
The Tornado is snake oil. With all the pressure on car companies to obtain a high CAFE number (corporate average fuel economy) don't you think they would use it, and provide it as standard equipment, if it worked at all? You bet they would. Don't waste your money.
I can't help you with the other two.
Corvette guy, mostly lurking. Love non-Bangle Bimmers.
77 C3 Corvette, Corvette Light Blue on Smoke Leather
355ci balanced and blueprinted, GMPP Vortec Heads, Keith Black flat top pistons, Comp Cams 268H, Edelbrock carb and Vortec Performer intake, 2200 stall converter
85 C4 Corvette, Medium Gray on Medium Gray leather
Bone stock, as the Good General intended.
Plus an 83 GTI, two Datsun Z's, a Mitsu SUV and a Hyundai. Still working on obtaining a partridge in a pear tree.