are you trying to start a firestorm?
Hi Ed,
I never try to start a firestorm - I simply apply logic & emotion (
just like you and everyone else does), hence the discussion thread:
- How to choose the right motor oil for your E39 by quality, cold-start, warm viscosity, slipperiness, and cost.
It turns out I believe that a human being's current motor oil selection is predetermined by their personality - well before they ever purchased a specific BMW.
Hence, as you know, we've collectively opined on the three or four BMW religious types (depending on the fluid, as coolant choice involved a fourth risk-taker experimental personality type):
- Fundamental BMW fluids decision-making religious camps (
1)
Specifically for motor oil, the three religious types will debate endlessly simply because the PEOPLE (not the oil) are different:
- Algorithms specific to motor oil selection (
1)
The three fluid types can perhaps be best summarized as the following:
1. BMW recommendations only
2. BMW recommendations + oils that meet BMW specifications
3. BMW recommendations + oils that meet BMW specifications + oil that meets high industry standards (e.g., API / SAE standards)
Getting to the point, this thread is all about viscosity - and specifically - how viscosity reputedly ruined an engine.
So let's look at what the
BMW owners manual says about viscosity:
Let's see what the Bentleys say about viscosity:
Bentley:
My owners manual says this about viscosity:
Now let's look at what the OP intimated:
- He says his owner manual "specifically says 5w30 0r 5w40 synthetic only".
- He says the indy purportedly put in "5W20 synthetic".
- The OP doesn't state the ambient temperature - but - since the 5 weight cold viscosity is the same in all three oils listed, I'll assume we're talking warm-running temperatures so we're talking about the 20 vs the 30 vs the 40 weight oil at engine temperature.
- He then intimates the 20 weight oil somehow ruined his engine (and only asks "if I have a case here").
A case?
- Note: We wholly omit any representations the indy made with respect to agreements, contracts, statements, etc.
- More importantly (as someone already noted), inexplicably, there is no diagnostic cause and effect established (maybe the engine overheated, for example?)
- So, it's way (way way way way) too soon to even discuss whether or not there is 'a case'.
But, we 'can' discuss what engine-temperature viscosity is appropriate for our bimmers.
Of course, BMW specifically omits any mention of 20-weight oil - so we need to dig a bit deeper away from the BMW Marketing Wizard-of-Oz, and a little deeper into engineering logic to find the answer to the OP's question.
Here's a chart of 20 weight oil in context with the 30 and 40 weight oil:
EDIT:
Here's another BMW-specific opinion on choosing E39
motor oil viscosity:
Note: It's hard to find SAE 20 mentioned anywhere in BMW land, so, this reference is kind'a old, but see "
The Ultimate Engine Oil Guide for E36 M3... First stop for any information/questions"