[T3] Diesel Oil, Flat Tappets & Gas Engines

Jim Adney jadney at vwtype3.org
Sun May 10 10:26:09 PDT 2020


Here's a chart that holds a LOT of info for those trying to decript the zinc 
content question.

https://lucasoil.com/pdf/Zinc_Values_MotorcycleOil.pdf

First, look at the top left entries, the zinc content of the Lucas Oil mainstream 
engine oils. Note that they all have SOME zinc; they are in 2 groups: the API 
(American Petroleum Institute) oils are just under 1000 ppm, while non-API 
oils are just over 1000 ppm. From this, I'm willing to conclude that present 
day API specs allow for some zinc content, so I was wrong when I thought 
zinc was forbidden in modern engine oils.

Second, look a the bottom right entrys. That's the zinc additive (Lucas 
#10063) I've been buying in small bottles. Note that all 4 lines there are for 
10063; they are just showing how much zinc you get if you add different 
amounts of Lucas 10063 to 4.9 qts of engine oil. Using the numbers Lucas 
provides on that page, I did the math, and 4 oz of 10063 added to 4.9 qts of 
any engine oil, will increase the zinc content of that oil by 1097 ppm, and 
adding 4 oz of 10063 to one of our 2.6 qt. oil changes will increase the zinc 
content of that oil by 2067 ppm, putting it right up there with their racing oils.

When I compare this to their classic car oil, lower left on that chart, and the 
racing oils just above them, we can see that the half bottle of 10063 that I've 
been adding to each oil change is clearly overkill, and 1/4 bottle might still 
be a bit of overkill.

I think I'll start using 1/4 bottle of 10063 for each oil change. At about $10 
per bottle of 10063, that's so cheap that I might start buying more 
mainstream motor oil, but one of the main things I like about diesel oils is 
that their Winter (that's the W in 10W-40) rating is not so low. 

VW originally specified straight SAE 30 or 40 for our cars most of the time. 
So I've always been hesitant about using multigrade oils, especially ones 
with wide differences between the summer and winter viscosities, because 
they are thought to break down to the lower number over time and heat. I 
used to use SAE 20W-30 or 20W-40, but it's been decades since I could buy 
those. Diesel oils are commonly available in 15W-40, so that's one reason I 
buy it. I would buy 15W-30 if anyone made it, and add 1/4 bottle of Lucas 
10063 to each oil change. Googling "15W-30" I find that it exists, but I 
haven't seen it anywhere in my limited local looking.

SAE 15W-40 was probably a good choice for the drive to the 2018 Invasion 
in Arizona, but SAE 40 would have been better. The heat on that drive was 
brutal.

-- 
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Jim Adney, jadney at vwtype3.org
Madison, Wisconsin, USA
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