The trend to lower viscosity oils is to reduce the power used to pump the
oil improving fuel economy. Thinner oil pumps easier. I have seem some
articles expressing concern about the impact of lower viscosity oil on
engine longevity, but as others have said you have to assume the engine OEM
engineers (and I am one) have assessed that impact and convinced themselves
that the engine will still meet useful life targets with the specified
oil.
That said, passenger car useful life targets are typically 120-140,000
miles. Most OEMs would say they met their target if 90% of the engines
that had the specified maintenance on a "typical" duty cycle lasted that
long. If your duty cycle is more severe than "typical" (and that can be
too low a load or too high a load) or you don't maintain it per the
schedule then you're likely to get lower life. Less stressful duty cycles
will make the engine last longer, but there is a point where increased
maintenance isn't better. I had a long argument while working a curve at
an autocross with a guy who was convinced that running high loads was good
for an engine. Not true. For example, a combine engine, with a duty cycle
that's 90% full load and 10% idle, will likely have a useful life (measured
in hours) that's 1/3 that of the same engine installed in an urban delivery
truck. Of course all idle and never warming the engine up will also cause
reduced life. In the end this is the literal meaning of YMMV.
Personally, the 0W20 and 5W20 scares me a little and so far I've stuck with
5W30.
Ben.....
On Fri, Nov 2, 2012 at 1:21 AM, Dave C <cavanadd@frontier.com> wrote:
> My wife and I are considering our third Subaru Forester. We have a 2000
> with 147K miles which is my daily commuter, and my wife has a 2008. We are
> considering getting a '13 model to replace my 2000. In talking with my inde
> Subaru mechanic (Subaru only, all former dealer mechanics) I found the new
> engine is a DOHC, chain driven cam, shim under bucket engine. So far, no
> big deal. I have been riding motorcycle engines with that technology for
> years, although if the valves ever do need an adjustment it's going to be
> ugly. However, apparently Subaru specs 0W-20 full synthetic oil for the
> engine. I was in the local chain auto parts store today picking up a
> couple of H4s and four five liter jugs of generic 10w30 that I use in just
> about everything and I saw that the ONLY 0w20 oil was Mobil 1 green cap,
> and it's REALLY spendy.
>
> We really like our Subarus. We live in rural Washington and live down
> about 2 miles of steep, semi-paved former logging road that gets snow in
> the winter some years, and the Subarus are all that keep us mobile. Do
> ya'll think this is anything to worry about? 0w20 just doesn't sound
> right...
> ______________________________**_________________
>
> Shop-talk@autox.team.net
> Donate: http://www.team.net/donate.**html<http://www.team.net/donate.html>
> Suggested annual donation $12.96
> Archive: http://www.team.net/archive
> Forums: http://www.team.net/forums
> Unsubscribe/Manage: http://autox.team.net/mailman/**
> options/shop-talk/bjzwissler@**gmail.com<http://autox.team.net/mailman/options/shop-talk/bjzwissler@gmail.com>
_______________________________________________
Shop-talk@autox.team.net
Archive: http://www.team.net/archive
|