Too thin mmm I think you are concerned about the wrong issue. To get a good answer I dug into this subject from the Oil guys perspective a while ago and this is what I wrote down so I could remember it if I ever had to come up with it again.
All oils are
designed to have a viscosity of 10 at operating temperature (212F
approximately). They are thicker when
the engine is cold. This is why engine
wear occurs at startup.
- -
Mineral based 10W-30 oil has a viscosity of 100
when cold and 10 when the engine is warmed up.
- -
Mineral based Straight 30 oil has a viscosity of
250 when cold and 10 when the engine is warmed up.
The quicker
your car oil get to the viscosity of 10 the better off you are. Synthetic are a little different
- -
Synthetic 0W-30 oil has a viscosity of 40 when
cold and 10 when the engine is warmed up.
- -
Synthetic 10W-30 oil has a viscosity of 75 when
cold and 10 when the engine is warmed up.
- -
Synthetic Straight 30 oil has a viscosity of 100
when cold and 10 when the engine is warmed up.
This property
along with it actually clinging to the engine parts better is why there is less
engine wear using synthetics.
It is also why synthetics leak (less viscosity) more than
mineral oils.
Now for ZDDP
requirements most people that seem to know oil are not into using
additives at all. They recommend finding oil
that has the blend of additives that you need mixed in with it. The only notable exception is breaking in an
engine.
Flat Tappet
cams ZDDP recommendations range from 1000ppm to 1800ppm with over 2000ppm considered excessive
and could be harmful. Most recommend 1200ppm to 1600ppm.
This is the
story on the lowering of ZDDP standards for engine oil. The standard is set by the American
Petroleum Institute (API) and the International Lubricants Standards Approval
Committee (ILSAC). Prior to 1988 API SF
specified a minimum of 1500 PPM
P. In 1993 API SG reduced the
minimum to 1200 PPM, and it was
reduced again to 1000 PPM with
the SL specification.
A broad wave
of flat-tappet camshaft failures started in 2004 following introduction of API SM and ILSAC GF-4 oil specifications which set a maximum of 800 PPM and a minimum of 600 PPM P for grades SAE 0W-20, SAE 5W-20, SAE 0W-30, SAE 5W-30
and SAE 10W-30.
For a good source of oil
Brad
Penn seems to have the range and numbers.
Keep in mind the higher number mean less oil flow went the engine is
cold. It does not make a lot of difference
when it is hot and almost none at all at normal operating temperatures.
It is the
startup and sitting around where synthetics may leak (less viscosity) more than
mineral oils.
Also in cold
weather Oil separates from it's additives and goes bad.
Spring time oil change is a great idea for you guys that store your cars
for the winter and not a bad idea for everyone. (ps less of an issue with
synthetics)
Mineral base
multi-grade mineral based 5W-20 is close to synthetic 10W-30 in cold thickness
and is a good choice for those that want to use mineral based oils.