BMW recommends Shell gas, but it's more expensive than other brands

[RockCrusher]

Originally Posted by F32Fleet

There was talk years ago that NITRO contained a UCL which reduced enough friction to show up as tiny gain in TQ/HP.

Did not get the impression the gain in power/torque when Shell gasoline was tested was due to reduced friction.

While my info is premium gasoline can contain a bit more energy than regular gasoline the difference is not significant.

The primary benefit of premium gasoline over regular is -- for engines that require it due to higher compression/better cylinder filling (due to turbo/super charging) -- the better resistance to detonation so the engine controller can use more timing advance.

In the test both test vehicle engines were tuned to run best on premium gasoline.

The gain in power was I believe due to better combustion.

[RockCrusher]

Originally Posted by Elderado82

All I know is that Shell gas here in NE is trash. I was regularly putting Shell in my M340i until it started having rough cold starts and wouldn't remote start anymore. I figured I'd try another gas to see if maybe I got a bad fill, so I went to Phillips 66, and the rough cold starts stopped. After a couple more tanks of Phillips, everything was good.

Being a BMW, I thought maybe I should go back to Shell, and well, what do you know, the car started running poorly again. Funny thing is, I even went to a different Shell station. So I went back to Phillips and had no problems.

About six months have passed, and now just about every Shell station here is turning into AMCO. Hmmm... has Shell turned into trash gas? This is just my experience here in NE with Shell. Has anyone else run into this?

Also, before you go on about spark plugs, fuel systems, and blah blah blah... I've already thought of those things, checked for cylinder issues and fuel system issues, and everything runs fine when not using Shell.

I haven't bothered to check my M2 owners manual but with other car brands there was kind of general recommendation in the fuel section that if the engine reacted unfavorably to a specific gasoline to switch brands.

So you did the right thing switching from Shell to Phillips 66.