OIL Controversy! *argh not another*

[Steven Ritchie <sritchie@xxxxxxxxxxxx>]

So I've recieved several emails telling me why I'm wrong about 10w30
synthetic being good all year round.  I'm more than willing to be PROVEN
wrong, but there's the rub.  No one has PROVEN that 15w50 is better given
all of the compromises or that 10w30 is bad.  Here are some of my arguments:


1> If 10w30 isn't good for the summer months in any part of the country why
do many japanese cars recommend it all year round?  Do German engineers
know something that the Japanese don't or do they run hotter engines?  How
is this engine different?

2> The manual that came with my car clearly shows that standard oil 15w40
is recommended all year round for the climate that I live in.  (Houston)  I
find it very hard to believe that I absolutely have to have 15w50 synthetic
oil in my engine or will fall to pieces when a 10w30 should perform
superiorly to a 15w40 standard oil.

3> I've read MANY MANY posts about oil on the digest and there has NEVER
been a clear consensus on what's best.  If there had been I would be using
it.  It's always pure conjecture and very little science mixed with a
healthy dose of anecdotal evidence.

4> The pro's and con's of using a higher weight oil MUST change
CONTINUOUSLY over the spectrum of oil weights.  It's not like 10w30 will
suddenly exhibit ZERO protection or 15w50 will magically ensure zero wear
in an engine.  There are tradeoffs and I have not seen any data to support
the notion that 15w50 is absolutely necessary.  Keep in mind that I'm
talking street application here, not racing.

5> FACT: Higher viscosity oils are less fuel efficient, therefore they must
cause energy loss vs lower weights, therefore the car must accelerate
slower.  The REAL question is, how much slower?  Would it be noticeable?

SO, I'm am saying that what I believe is from anectodal experience mixed
with my common sense and the belief that very few people know what they are
talking about when it comes to motor oils. (including me)

I don't mind that anyone disagrees, however they presented some real
evidence they could probably convince me of their correctness.  I don't
think that I'm necessarily right either, but in the absense of good
evidence that it makes a difference either way, I going to try more gas
efficient/less friction/possibly faster 10w30 oil.

So please tell me why I am wrong and back it up w/ evidence.  I would be
more than happy to admit that I am completely wrong, but I got's ta see
some paperwork.  Also keep in mind that this is generally for street
driving, not 10 hours @ 6000RPM...

Steve

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End of bmw-digest V9 #401
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