Bill Babcock wrote:
>
>I suspect that any oil company chemist could make a good impression about
>oils. But the thing I thought was remarkable was that he was very specific
>about what Redline oils NOT to use. He didn't recommend the low initial
>weight oils (like 5w50) because the plasticizers they need to add don't
>necessarily provide sufficient viscosity at higher RPM.
Bill brings up a good point. To make a multi-grade oil like 5W-50, they
start with oil that meets the low temperature SAE Grade 5 spec and put in
additives that expand with temperature to make the oil meet the high
temperature viscosity spec for SAE grade 50 oil.
Trouble is, these additives DON"T DO ANY LUBRICATING. The farther apart the
two grades are, the more additives they have to put in. A quart of 5W-50 has
less oil and more additives than 20W-50. I would imagine that the lower the
W grade, the more additives they have to put in to get it to meet the hot
spec also.
So when you buy a quart of 5W-50 grade oil, you are getting less oil than if
you buy SAE 50 single grade oil.
The reason for multi-grade oil is for easier winter starting. The ONLY
reason.
Since I only start the race car in the summer, I use single grade SAE 40 or
50 grade Castrol.
Actually, the real reason is that it somehow seems more British.
John Herrera
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