I sort of agree with Mike.
However, in reading through the very confusing API standards, it appears
that some weights of oils may somehow be rated SM & still have higher
levels of Z & P. The oils which "have" to have reduced ZDDP, safe for
catalytic converters, are the oils which would be used in newer engines,
eg, 5W-20, 10W-30 etc. You have to read through a lot to find this.
http://www.api.org/certifications/engineoil/pubs/upload/1509_16thedition042007.pdf
As Editor Gary said earlier,
"on the MG list and 20W50 is NOT used in modern cars AFAIK. They all
require a
much lower weight synthetic oil. Hence it is quite plausible that an oil
company might be putting different amounts of ZDDP in their different
weights of
the same brand of oil.
Just the facts, ma'am.
Cheers
gary"
The SM rated oils in higher viscosities such as 20W-50 "may" not have to
have reduced ZDDP content since they are unlikely to be used in later
cars with catalytic converters. But if so, why are they allowed to have
the same SM rating as the reduced oils? The API specs are confusing &
the oil companies', published information is ambiguous at best.
Valvoline has two 20-50 "Racing" oils. "Valvoline Racing VR1" part
#VV211, which is marked SL/SM & also a 20-50 "Valvoline Racing" part
#VV851, oil which is marked for "Off Road Use Only". It is implied that
the "Off Road" has more ZDDP but no detergents & would require very
frequent oil changes. Their published Z&P content on the two oils is
conflicting.
Since I have an ample supply of the original GM EOS, guess I'll continue
to use a pint with each change of VR1 20-50 street oil.
Regards,
Dave Russell
M Lempert wrote:
> First I must admit I'm no expert on this issue. I have been using
> Valvoline VR1 20-50 based on product data and Michael Salter's blog.
> I have no reason to believe VR1 isn't a good choice. However, if I
> remember correctly, the VR1 bottle had a double API rating of SL/SM.
> That caused me some concern as anything SM indicates current
> generation and safe for catalytic converters. I really don't
> understand how it can have both ratings. I'd feel better with
> something that would be very bad for catalytic converters.
>
> ------------------- ----------------- Regards, Mike Lempert
>
> > Mike,
> >
> > Could you tell us all why exactly you would move from VR1?
> >
> > Robert.
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