Dr. Lee,
A while back I recall reading that you recommended adding STP oil treatment at an oil change due to its anti-wear additives that are not included in motor oil as they are bad for cat converters.
My questions are, how much do I add for my Duramax 10 quart capacity, and do I use the blue bottle formula, I also recall seeing a red bottle
at one time.
Thanks,
David P.
" LET'S ROLL.... "
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Hi David:
STP contains the beneficial additive zinc dithiophosphate, containing (in addition to zinc) both sulfur and phosphorus, which can poison automobile catalysts. If you can find the red bottle for 4 cylinder cars, it has less of the oil thickener, that we don't need. If all you can find is blue, that is OK - I have used blue for years and am just now switching to red.
For the 10 quart engine I would still just use 1/2 bottle per oil change, about 7 or 8 ounces. That will add a nice dose of zinc dithiophosphate without overdoing the oil thickener.
Dr. Lee :cool:
