motopokep

So I went to O'Rilley's auto parts to buy oil for my '04 530. I decided to go with 5w-40 instead of 5w-30 as extreme cold tempereature is still coming in February. The only one they had was Mobil 1 Turbo Diesel Truck 5W-40 and I told them I don't have a turbo diesel engine and they said it doesn't matter, you can use it on a regular engine.

When I search for oil for my car on Mobil's website, they recommend Mobil 1 0W-40, while my manual says either 5w-30 or 5w-40.


Should I return the Turbo Diesel? Something tells me I shouldn't have bought it in the first place.


Should I go with 0W-40, or 5W-40, or 5W-30. I'm in Chicago, we get -5 F in February and up to +95 F in the summer.



Thanx

response_surface

diesel oils meet or exceed the the requirements for gas engines. i use rotella fossil 15-40 in all my vehicles except the ones that require synthetic. i use rotella in all 3 of my motorcycles too, and the top end is much quieter, and the shifts are smoother.

if you use a synthetic diesel oil you'll be fine. oil for gas engines cannot be used in diesels, that says it all imho.

i'm actually considering rotella 5-40 syn for my 545i and wifey's A8, since it can be bought in gallon containers and is cheaper than mobil syn.

turboawd

5w-40 is thicker than 5w-30

motopokep

And being thicker, it is better for colder temperatures, right? Everyone says so.


So ok to use diesel then...thanx. Responce surface, since you also have an Audi (I do too, Q7), ok to use this same oil in the Q7? The manual says only to use oils that have some VW 502 00 standard....

Rizbel

No, it's the opposite. Colder temp needs lower viscosity for oil to properly lubricate the engine.
But I think you're fine with 5W-40.

response_surface

yes, i use mobil syn 15-50 in both the 545 and the A8. i'm sure any syn oil meets the 502 spec. they say that to get you to buy a rebadged syn oil that says vw on it. don't know who makes vw oil, but bmw oil is castrol syn. i don't really like castrol syn b/c its not a "true syn", just mega refined fossil oil with loads of additives. mobil is a true syn, there was some series of lawsuits from mobil years ago about synthetic claims.

5-30 and 5-40 have about the same viscosity at 20 deg C. the 5-40 retains is visc better at 100C, b/c of massive additive package. it means that at 100C it has the same visc as a 40wt would at 100C.

i don't use 5-40, experts say to stay away from multi visc oils that have too wide of a range, the visc inhibitors break down after a few thousand miles. although they may have improved in recent years. my friend runs rotella 5-40 syn in his diesel VW, has almost 300K on it, what does that tell you?

don't get too hung up on oils, just change it when you should with a good synthetic. any decent engine will last 200K if you do.

this is all you ever needed to know about oils

http://micapeak.com/info/oiled.html