engine oil weight question

[m5bbq]

my car sticker calls for 0w30 oil. I hear everyone going with 5w40. Is that necessary? Are there reports of engine failure with 0w30? or is heavier weight only for people running aftermarket tunes & bigger turbo?

[M5_Raz]

Mobil 1 0w40 only for me.

[vafan13]

40 weight ended up being added as an optional oil choice for our cars sometime after they were originally released, so there's nothing wrong with using either. In general folks feel safer with 40 weight and some, like me, have seen reduced oil consumption. I imagine the tuned guys are even more likely to run 40, but it certainly isn't limited to them.

Whether 0w40 or 5w40 would be better is dictated largely by which oil one uses. For some, like Mobil 1 and Castrol Edge, the 0w40s have historically been higher quality oils than their 5w40 counterparts. Another thing to note with 0w40s is they are on the lighter end of 40 weight, so less drastic of a jump from a 5w30.

[m5bbq]

thanks for responses. I get the argument of heavier oil = better protection but what about the bearing gaps? I heard f10 bearing gaps are pretty tight. In E60, we go thinner to make sure the oil gets between the tight bearing gaps (or change rod bearing). Wouldn't heavier oil potentially starve oil at the bearings at high rpm?

really would love to know what oil people were using when their engines gave up in our platform.

[vafan13]

i am no expert, but...the rod bearing clearances for the S63Tu (.025-.070mm) are much bigger than the S65/S85 (.010-.034mm) and we're talking 0w40 or 5w40 in the S63Tu versus people dropping down to 5w50 in the S65/S85. If the latter combo has no issues getting oil between the bearings I don't see how the former would.

Probably more important than 5w30 vs 0w40 vs 5w40 is making sure whatever you choose has a low NOACK and high HTHS and frequent oil changes (esp. with the 30 weight).

[bigmixx11]

Originally Posted by m5bbq

my car sticker calls for 0w30 oil. I hear everyone going with 5w40. Is that necessary? Are there reports of engine failure with 0w30? or is heavier weight only for people running aftermarket tunes & bigger turbo?

From what I've read, it seems like there are several factors involved in deciding which oil to use. Which year/generation M5. Climate where you live. How many miles you drive per year. How many miles are on the car. Tuned or not. How hard you drive it. Does your car burn oil. I think you need to answer all of these questions then decide which weight is best then choose your brand.

[Blaxwil]

Every so often this question pops up on the forum. It really doesn't matter. Just use the correct oil weight and stop overthinking.

I'm at 150k miles with 75k of them being tuned. I've only used two weights. 0W/30 from the dealer and 5W/40 since being tuned.

The key is to change your oil every 5-7k miles.

[M5_Raz]

Originally Posted by Blaxwil

Every so often this question pops up on the forum. It really doesn't matter. Just use the correct oil weight and stop overthinking.

I'm at 150k miles with 75k of them being tuned. I've only used two weights. 0W/30 from the dealer and 5W/40 since being tuned.

The key is to change your oil every 5-7k miles.

Does your oil smell like gas after a few thousand miles?

[Blaxwil]

Originally Posted by M5_Raz

Does your oil smell like gas after a few thousand miles?

No never smelled fuel in the oil.

[M5_Raz]

Originally Posted by Blaxwil

No never smelled fuel in the oil.

Interesting, even when you open the cap? Do you still do blackstone oil analysis? I submitted one recently and am waiting to hear back.

[m5bbq]

fuel in oil usually means the engine is running rich. It may be from an aftermarket tune or fouled plugs. I'm doing oil change now, and no fuel smell at all. Mine's stock. if you're running a tune, which one are you running?

too bad that oil drain plug is basically the lowest point of the car. I wanted to put on fumoto drain valve but I am worried it will poke out below the level of the subframe plate. One bad bump or rock can take it out and drain all the oil on the road! back to the traditional drain plug and returning the fumoto.

[m5bbq]

I had to put 9qt in after the oil change. I just jacked up the front of the car and I let it drain for a couple hours. It becomes dribble in few minutes but that dribbles keep on going for an hour at least. More the reason why nobody can beat DIY. Dealers will most likely plug the drain after 5minutes.

[vafan13]

Originally Posted by m5bbq

I had to put 9qt in after the oil change. I just jacked up the front of the car and I let it drain for a couple hours. It becomes dribble in few minutes but that dribbles keep on going for an hour at least. More the reason why nobody can beat DIY. Dealers will most likely plug the drain after 5minutes.

It does drain for a surprisingly long time. I put a measuring cup under it once it got to be dribble-ish stage and while i don't remember exactly how much I ended up with, it was a lot more than I expected.

As an FYI, the one blackstone I did had 0.5% fuel. Will try to do another one with this upcoming oil change to see if it's any less with the new plugs.