Originally Posted By: 440Magnum
Originally Posted By: Kuato
In many cases this may be true. But why would vehicle manufacturers, worldwide, recommend thicker oils in all their vehicles? The thinnest I saw in any of Shannow's manuals was 5w30. What makes 0w20 a magic elixir in the US but nowhere else?
Its weird, but to me its weird in the opposite way its weird to you. In my lifetime, the THICKEST recommended oil for an ordinary passenger car in my area was 10w40, and that was 40+ years ago. When I was a kid (70s) the "really old cars" we played with- circa 1940s thru early 50s, were usually spec'd for straight 30 weight, not straight 40 or 50. For the next 20 odd years, 10w30 was the norm, and a 15w40 was a diesel engine oil you might use in a 400k mile worn-out engine to eke out a few more years. 20w50 was extreme race engine oil, not anything ANYONE would consider driving on the street, even in the desert southwest where 110-115F is common ambient temperature and the freeways are LONG and straight.
And yet, none of these cars that now run on 5w20 seem to blow up or live short lives... quite the opposite in fact. My conclusion is the rest of the world specs oil differently than north America simply because, for whatever reason and it WASN'T fuel economy, American manufacturers were already building with the intent of Xw30 being the maximum viscosity all the way back in the 60s and 70s. GM specifically said their de-endorsement of 10w40 back in the 70s was due to deposits formed by the VI modifiers typical of 10w40 oils of the day. Whatever the cause, the supply infrastructure was already geared up for 10w30 and 5w30, and when Ford started moving Xw20 into the supply stream in the early 90s, it was just not a big deal. Now its the norm.
People say that in the rest of the world, oil is spec'd by engineers for longevity and in the US its set by bureaucrats for emissions/efficiency, and there may be a grain of truth in the latter. But a) it hasn't HURT longevity at all, and b) the argument could just as easily be made that the rest of the world is clinging to outdated viscosities just because of the inertia in the supply chain.
I started to spend time in North America in the mid 70's, comming from the UK Being interested in cars a couple of things struck me.
1) Lighter oils were used, 10w-30 was on the rack at every gas station.
2) People paid more attention to motor oil. Guy's would talk about doing an oil change and what brands they would use. You would often see people checking their oil at a gas station.
3) Considering car engines were very much larger. Car trips were typically longer (lots of short trip use in the UK) and usage was typically gentle (no thrashing on the motorway) Engines were NOT LASTING MUCH LONGER than a typical 4 banger would back in the UK. 100k.
When I bought my first vehicles here my thoughts were, the climate here Vancouver Island is similar or warmer than the UK, I have a 2 litre engine like I might have in the UK, so I'll use 20w-50 oil like I would in the UK.
