Motor Oil Recommendations

[50/50]

Did a search in the Technical forum to see what the current thinking is for motor oil in a low mileage engine.
But didn't come up with anything conclusive.
What are you using? Brand, weight, synthetic, petro based, Zn, addititives?

[lopena]

I use Castrol GTX 20w50 conventional oil in my ‘69S…available from walmart.com ($23 for a 5 quart jug).

Alan
N.J.

[72targa]

This seems to be the current go-to for our early air cooled engines…

https://penngrade1.com/products/high...il-sae-20w-50/

[Chuck Miller]

Plus 1 on that ...

[Frankr]

Valvoline VR1 with zinc. https://www.valvolineglobal.com/en/vr1-racing-oil/

[HarryD]

I have been using LiquiMoly Touring Hi Tech 20W-50. i used to use BradPenn/Penngrade but (per LN Engineering) Lubrizol stopping making the additive package they originally used.

[72targa]

Ahhhh, engine oil…the eternal debate. Based on the few comments in this thread, I did a little recheck on the market.

As background, I worked for Chevron Lubricants for 36 years so I have a little personal bias towards Chevron products. With that said, here’s what I use currently in my ‘72 S:

https://penngrade1.com/wp-content/up...-Oils-2022.pdf

I use it because I trust the logic of a product that contains 1500 ppm Zinc for my old engine. There are only a handful of oil additive manufacturers that make engine oil DI packages and they’re all top notch. The fact that LZ is no longer involved just means that DA Lubricants has decided to switch to one of the other limited options (again, all good as they all formulate to specs and desired performance levels). Let’s look at some other oils.

The product that I would be very satisfied to use if not for the Zinc issue is this…

https://cglapps.chevron.com/msdspds/...&docFormat=PDF

Havoline Motor Oil 20W-50 is an excellent oil in the desired viscosity grade. It is an excellent oil based on the additive package in use. That said, the additive package is designed to be used with catalytic converters. There are limits as to how much phosphorus can be in the engine oil so as to not destroy the function of the catalytic converter. Because the zinc we all crave comes from the ZDDP (Zinc dialkyldithiophosphate) additive commonly used, the amount of zinc you get is correlated with the amount of phosphorus you get. High zinc = high phosphorus. Low zinc = low phosphorus. The zinc in Havoline 20W-50 is 870 ppm and the phosphorus is 770 ppm. Great for cars with catalytic converters but not right for my old S.

Next up, Valvoline VR-1 20W-50…

https://sharena21.springcm.com/Publi...0-ac162d889bd3

Most likely an excellent oil for our cars, but only 1400 ppm zinc. For now, I’ll stick with the Brad Penn product, purely for the zinc level plus I tend to avoid switching just to switch (but I can’t fault this oil based on the argument being discussed).

Finally, the Liqui-Moly product…

https://pim.liqui-moly.de/pdf/en_US/liqui/52/P000213

As the product data sheet indicates “Tested safe with catalytic converters and turbochargers”, and based on the ZDDP discussion above, I would be amazed if the Liqui-Moly product is high zinc (it is most likely similar to the Havoline product but sadly, they don’t list their zinc content).

Clear as mud?

Probably most important of all is maintaining the proper level of oil in our dry sump system and changing it regularly. Hope this is all helpful.

[50/50]

Yes, a much debated ,and based on most of our duty cycles , overexamined topic. However thanks for all suggestions and Peter K's learned reasoning.

[HarryD]

Peter. Thanks for your insights.

FWIW, part of my choice to go with LiquiMoly is based on the fact the formulation conforms to the API SL Specification as opposed to later ones which apparently mandated lower ZDDP.

[RSTarga]

Always a very controversial topic. I've used Mobil 1 15w50 for 40 years on all my air cooled Porsches with never a problem. Get it at Walmart in jugs for around $30 per jug. Change it twice a year or every 5k miles which ever occurs first.