Times have definitely changed, oil has changed. If you drive a car that dates before 1995 today's oil will not work because it does not have Zinc Phosphate.
This is interesting, especially since my 1985 Jimmy, my 1971 Riviera, and my 1973 Riviera, as well as my dad's 1979 Chevy van all seem to do fine with "today's oil".
Fuel additives like "sea-foam" do not publish their ingredients. I will shop around to see if I can find an MSDS on that product. I do know that if you put that "junk" in your vehicle and it is not a 1978 Chevy, well I personally have dumped over 50 gas tanks with that stuff in it because it broke loose so much crap it filled the exhaust with an oil that saturated the catalytic converter so bad all it did was smoke.
This is also interesting, since when I used the SeaFoam on my Jimmy, my Suzuki Swift, my mother's 1997 Riviera, and my fiance's 1997 Riviera, I don't remember noticing "all it did was smoke" in any of them. The good news is I just bought two more cans of SeaFoam today, so I can pay extra particular attention to the exhaust for all that smoke.
But before you "hate" on salesman, just know that I have documented proof, or you can go online and check out the product for yourselves, there is no "selling".
I'll do a lot better than read "documented proof" online - I'll prove it (or disprove it) for myself. Then that will be online, too - on this site.
As long as am a member of this site i will provide any and all information about vehicles that you would like,
OK, what's the best way to go up a hill for the best gas mileage? That's one I haven't been able to figure out yet.
Hey wmjinman, I need to know what kind of vehicle you have,
2000 GMC Jimmy 4-door, automatic trans, 4 wheel drive (and the color is white. ...I expect that's critical, too) how many miles per month you track,
varies - maybe 400 to 500,a list of all of your mods,
grille block, 60 psi in the tires, roof rack delete, mirrors folded back, fuse for interior lights removed area,
43.26 sq. ft. and average nominal atmospheric temperature of your location,
varies between the low teens to the mid 90's. Think I read somewhere the average is around 50 products you have used,
Have used or currently using? gasoline: Arco 87 octane, antifreeze: Prestone, headlights: Sylvania, belts: Gates, fiters: Fram, tires: Uniroyal Liberators, wiper blades: Ecko, toothpaste: Aim.....type of oil you have used,
Pennzoil 10/30 engine size,
4.3 liter Vortec tire size,
235-75/15 and where you get your information.
My own personal testing following MetroMPG's method described elsewhere on this site
I may possibly have a great deal of information for you to use, hell maybe I could increase your mpg's by 25%
With the first 5.7% being from that AmsOil P.I. fuel additive, right? Let's see how that works out & then take it from there, eh?
just by offering simple suggestions that you may not have thought of,interested?
Absolutely! ....Starting with the best way to go up a hill for maximum MPG.
Keep in mind that I do this for a living and have access to all publications, TSB's on every vehicle, and my customer base is 30,000 people deep
WOW!!! Mechanic for 10 years with 30,000 customers..... hmmm, that would be 3000 per year, or around 10 a day. Whoa, busy boy - makes me wonder why you don't own your own house by now.
I would love the opportunity to explain all aspects of automotive engineering, industrial engineering, industrial electricity and electronics,
Uh, are you sure you have the time - with your 10 customers a day and all?
and simply "what works and what doesn't".
Hey, how about that hydrogen generator!!!
(from the "beaker" profile and "planned mods")
Every product on the market has been tested in my shop.
Wow, really?!?!?! Every single one? Holy smoke - Boggles the mind!!! 
I also homebrew fuel additives that are substantially less expensive to make if you are also interested.