I thought that zinc dialkyldithiophosphate, or zinc di-thiophosphate were additives in all gasoline and diesel engine motor oils, but with reduced concentration in more recent oils.  However, there remain specialty oils (for classic car engines, motorcycles, heavy trucks, racing) that have the high concentrations of older oils.  If you have something that really needs the extra zinc/phosphorous additive, you might seek out one of these oils.    I thought that Kendall was generally considered a lesser quality oil compared to some other brands.  At one time it was the oil of choice by cheap fast lube places.  I think Firestone used it extensively, also.  mcneely

---- John Rodgers <jrodgers113@GMAIL.COM> wrote:
> Kendal oil seems to be a really good oil. I have had several cases of it
> thru a windfall, but I am down to the last few quarts. Can't seem to find
> it anywhere. A 'Net search turned up a little info - company is now part of
> Conaco-Phillips, with the trade name Kendall Oil GT-1 belonging to 5hem,
> but the actual Kendall oil being made elsewhere. The original oil had a
> zinc compound in it that helped the engines, and the oil was made from a
> really sweet crude. Anybody know more. Sure would like to get a coule of
> cases of this original Kendall GT I.
>
> John

--
David McNeely