[digital717]

I don't know what's best, but I run Pennzoil Platinum Euro 5w40 since it's the OEM oil, it's readily available locally, and it's cheap. Advanced Auto Parts has it on sale all the time for $28.99 for 5 quarts. Can't beat that.

[SteveInfante]

I used Castrol Syntec 0-40W for almost 100K in the N20 in my 228i. Never had an issue. With the F31 I switched to M1 0-40 and now I'm on the Rotella T6 5W-40 train because #boostedcarsloveit. for less than $50 for an oil change including the BMW filter kit from the dealer it's hard to beat.

[B58 parts]

Well the other day I put the Valvoline 5w40 diesel into the b58.

The idle is way smooth. I posted here before about a shitty idle .. 0w20 sucks .. maybe? I don't know I'm not an expert .. FFS i'm running diesel oil based on a couple forum posts. But it sits level at 700 can't even feel it's running. The cold start delete is satisfying.

The first 0w20 analysis came back A1, I'll send this one out also but I am looking forward to sending the 5w40 next.

It seems to like it so far. The weather has been shit but finally I got a few good pulls in and all is well. Much is due to the new map but it is so smooth, I don't know how much an oil can contribute to that but it's working out ok for week 1. I need to do the brake kit and look at some squeeky noises..

[Makerveli]

Originally Posted by Zanity

I switch from Liqui Moly to this, Pennzoil is the actual BMW factory OEM oil, I use 5W-40, because more viscosity = less engine wear, at the cost of a bit of mpg, which I'm ok with.

Can I ask why the higher viscosity causes more mpg? Does it have to work harder?

[F32Fleet]

Originally Posted by Makerveli

Can I ask why the higher viscosity causes more mpg? Does it have to work harder?

Assuming you mean a mpg penalty.

Higher viscosity oils increase the amount effort required to pump the oil. It takes a couple of extra HP which reduces MPG. Especially during the start up phase when all oils are significantly thicker than the hot temp viscosity of the heaviest grades.

The pump doesn't work harder because it's driven by the the crankshaft via chain. The engine works a little harder.

Depending on the engine under test conditions moving from a 40 grade to 20 grade could increase MPG up to 2--3%. This savings adds up over tens of thousands of units sold. It's a race for avoiding CAFE/Emissions penalties.

[Smooth_Operator]

I use Liqui-Moly 5W40 from FCP Euro and use their 'lifetime replacement' program. Pretty sure ECS tuning offers the same thing now with a wider selection of oils. Effectively reducing the cost of each oil change to the cost of shipping the used oil back to Connecticut. Granted the refund comes in the form of store credit... but let's be honest I drive an 11 year old BMW so the money is getting spend on parts anyway lol