Oil threads never go anywhere productive.

The net effect is something XX/40W or XX/50W, and a diesel rated oil can't hurt. 30W is too thin for your climate and not recommended in the factory books. I would do some research though before we blanket assume all diesel oils have tons of zinc in them

I live in Ohio not SoCal so 20/50 makes stuff hard to start. I generally put 5/40 synthetic diesel oil in stuff, or 0/40. Because its usually easy to find and cheap at Walmart, Mobil1 has become my norm, but not for any real reason other than price and accessibility.

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