<VV> Diesel Oil in Corvair

[Dale Dewald]

At 17:59 3/10/2011 -0500, J R Read wrote:

 >>snip<<

>What I was trying to get at was the ZDP levels in various Mobil 1 products.
>The 15w50 is 1200ppmPhosphorus and 1300ppm Zinc and is recommended for flat
>tappet applications.  The "Turbo Diesel Truck" version is 1100ppm
>Phosphorous and 1200ppm Zinc.  This is the one I have been using but have
>recently found it hard to find.

The P and Zn levels in the Mobile 1 "TDT" 5W-40 should still be adequate 
for a properly broken-in, well maintained engine.  If you can still find 
this formulation, I see no reason not to continue using it.

>This caused me to re-think about whether or not I should even be using an
>oil indicated for diesel engines at all.  The viscosity level of the
>"diesel" version is closer to the 10w30 I would like to be using than the
>15w50, so that is another consideration.

To my mind the viscosity issue is more significant than the enhanced 
additive package found in a diesel rated oil.  For the most part gasoline 
engines do not need as much of these additives to meet the service life of 
the oil, so it is somewhat a case of overkill.  I have never found a diesel 
rated oil that does not also have an API S-rating for use in gasoline 
engines. However, most of the oils sold for use in gasoline engines do not 
have an API rating for use in diesel engines.

>So, my question is...  are there harmful effects to a gas engine when using
>"diesel" oil?

As far as your gas engine is concerned, no. However, there might be some 
minor harm to your pocketbook for higher price of the diesel rated oil.  I 
believe that the extra price is well justified if the diesel oil you 
purchase contains sufficient P and Zn.

Dale Dewald
Hancock, MI