It don’t matter

[Krooser]

Never had an oil related failure in anything I've owned...street or race.

Ran a 25 feature years ago with a broken oil pump laying in the oil pan. Broken gauge. Amsoil...never hurt anything.

Got a friend who runs Wally World oil in his dirt car. Cheap bastard like me. Seems to work.

I run what ever is on the shelf in my 285k Ram...no issues.

Had the best luck with Delvac and Lucas additive in my last 3406 Cat....2,000,000 miles before I did a major

[BradH]

Politics, religion, oil... three subjects I've learned to never bring up in conversation anymore.

[Alaskaracer]

There's so much misinformation on oil out there it's simply stupid. What most aren't talking about is a lot of the "cheap" oils such as Wally World oil are just rebranded oils like Valvoline! Same oil, same standards, same quality, different bottle....

Now, getting 10-15 hp from an oil change? Not likely.....Unless you're running 140w and switch to 10w! If there's that much friction inside your engine and a simple oil change makes that much difference, SOMETHING IS VERY WRONG!

In regards to Amsoil, I'm gonna call bs on that as well. NOT BECAUSE I'M A DEALER.... I run it in all my stuff exclusively, including my 1510 hp dragster engine...(yes, I have the dyno sheet to prove it). It gets Amsoil 15w50 racing oil. As to my daily drivers, my car runs 0w20 per factory specs and my truck gets 15w40 (diesel). One thing I can say, is that in BOTH of my vehicles, I have gotten a noticeable increase in fuel mileage running Amsoil over other oils. In my truck, I average .5-1.5 mpg increase depending on city or highway driving when running amsoil. I drive it a lot and track my fuel and mileage very carefully. I've done 4 oil changes with different oils before and my economy dropped in EVERY CASE. Went back to Amsoil and economy came back. Same as in my car. Now, is there any difference in power? I can't tell a thing except when I go to the pump. And given that I drive both an average of over 2000 miles a month, I'll take what I can get.

[Roundybout]

I would think getting better mileage with just a change of oil brands (same viscosity) has to be due to better efficiency. Doesn’t better efficiency = more HP? Or is it less fuel needed to make the same HP?

On a 1000HP engine gaining 10-15HP from a simple oil change using the same viscosity is less than a 2% gain and believable in that scenario. Getting that much HP on a 400HP engine would be a different story. I also think one brands 10W30 can be a slightly different viscosity than another brands 10W30 and could account for a slight difference in HP.

[quickd100]

I work for farmers. Long ago we settled on running 1 engine oil in everything from weedeaters to diesel tractors. It just happens to be 15/40 Shell Rottela HD Diesel oil. Probably better than some maybe worse than others. In the 30 years we've used it we've never experienced a oil related engine failure.
Having said that, a few years ago a guy drove in the yard in a Justice Bros. truck. I really didn't feel like suffering through a long sales pitch so I handed him to the bosses son. The bosses son had recently switched to John Deere brand oil in his JD equipment as they offered an extended warranty if you used their oil.
The sales guy pulls out one of those (oil testing clear plastic gear train machines) they put some JD oil in it and it makes a couple revolutions and stalls out. He then cleans it up and puts some Justice Bros oil in it and it makes a couple more revolutions than the JD oil. I m watching all this from across the shop. I yell over, try some of our Rotella in it. The sales guy dumps some of our Rottela in it and the machine just keeps running and running. He didn't sell much that day.

[MadBill]

Since friction reduction and thus more net torque would be the expected direct benefit of the oils under discussion, RPM would be a big factor. A 5 lb-ft. friction reduction at 10,000 RPM would be almost 10 HP, but at 5,000 would be half that.

[ssdoug]

Most high grade oils do a good job for friction reduction . Find a oil package that works with your ring/hone package and you will find as much or more than friction reduction.

[BBO Omega]

For performance engines utilizing Hydraulic Roller Cams, heavier weight (20w50) oil has shown Horsepower improvements in numerous tests. Joe Sherman proved this multiple times.

I just posted this to stir the pot a little