| > You will probably get a plethora of opinions on this. I would look in | > the owners | > manual and see if 10W-30 is approved as an option for some temperatures | > or classes | > of operation. If so, I would use it.. | >
| > If not, I might be hesitant, especially if it affected the viability of | > my warranty. | | A bogus answer. The manual is not all knowing and all powerful. | Science matters too. A good 10W-30 is going to put less start up drag | on an engine in the summer months than a 5W-30 does in the winter. | Once warmed up, they are the same viscosity rating. All the 5W tells | you is that that oil has better extremely low temperature cranking than | does a 10W oil.
I thought this way too- until reading this:
Multi viscosity oils work like this: Polymers are added to a light base (5W, 10W, 20W), which prevent the oil from thinning as much as it warms up. At cold temperatures the polymers are coiled up and allow the oil to flow as their low numbers indicate. As the oil warms up the polymers begin to unwind into long chains that prevent the oil from thinning as much as it normally would. The result is that at 100 degrees C the oil has thinned only as much as the higher viscosity number indicates. Another way of looking at multi-vis oils is to think of a 20W-50 as a 20 weight oil that will not thin more than a 50 weight would when hot.
*(Not a 50 weight oil that will only get as thick as a 20 weight oil when cold)
From:
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correct, you have a 5 or 10 weight oil at start up that only thins asmuch as 30 weight oil at higher temperatures. At 70° F the 5 weight willbe thinner than the 10 weight.
*Added by me.