ryanhere

My 05 E55 (47K miles) has developed a Whirring sound on cold Startups'. This began happen after an oil change at the Stealership. The sound seems to quieten down after about a minute of running, but its still there.
I have since changed the Oil myself (Mobil 1 0w-40) swapping filters between Mann and Purepower metal filter. No change. The pulley's are all good.
I was told by a mechanic friend that this is due to the gears in the oil pump and that its common, but I'm not sure about his diagnosis. Sounds pretty bad to be a common occurrence.

Has anyone here heard this before or know what could cause this ?

Dublinoh

No expert here but make sure the fan isn't hitting the shroud or anything else. Does the sound pitch increase with rpm increase?

ryanhere

Fan clearances are good... the Sound pitch does increase with rpm's

fergsc32

that is absolutely the oil pump per your mechanic... remember there are iirc 6 metal gears in the oil pump....new and or different oil makes a difference....for instance.. when i use mobile 1 0 40.. it is the loudest....when i switched to bizol.. is was non existent.. i just switch back to the mobile 1 m formula 5 40 and its back louder again.... there are no issues that you have so rest easy...

ryanhere

Where did you obtain Bizol ? Can you please post the link ?
What spec oil did you use ?

Got it:
https://www.eeuroparts.com/Parts/869...rotect-B75511/

ryanhere

Ok.. I put in Bizol 0-40 and like mentioned by fergsc32 , the sound magically went away.
so what gives? I always thought Mobil 1 0w-40 was the gold standard, but I think not after this experience.

pumpedTSI

Not a fan of M1 oil......last change was Royal Purple which seems ok but think I will try Amzoil or Liquid Moly next time around......

kustom2k1

Thats the sound of money being sucked out of your wallet.

Dublinoh

I had the same thought LOL

Amazing that a change of oil could stop that.

MACEDON

That's normal bro. I changed from Mobil to Castrol and mine started making the noise. It goes away, completely normal.

Elhonaz

i allways had this same noise. On mobil 1 its loudest, now went with liquily moly leichtlauf 5w-40. its not as loud but def there. Can you take a video now with the bizoil? Cold start plz and after a while!

Max.H

Sounds normal, a lot of cars do that at cold start. Nice cobra tank, have you felt any difference with it on?

ryanhere

Here is the sound post Bizol oil change. No whirring noise. The cobra tank really helps IAT Temps. With dual H/E I see Approx 8-10 f above ambient while cruising and a 30-35f temp jump at WOT

Elhonaz

its still present on cold start.. but as the idle comes down its very quiet. What was the exact bizoil u used?

ryanhere

Yes, that's the pump noise at the start, pretty normal.. I got this oil:
https://www.eeuroparts.com/Parts/869...rotect-B75511/