What kind of viscosity do you guys have in your stovebolts? I´m using a mineral oil with very high zinc (2100ppm) additives and high viscosity in both of my Blue flame sixies. It´s called :Lucas Hot rod and classic 20W-50 Oil High Zinc
in a 235 I would use straight weight 30. Unless it is very cold or very hot in which case I may go up or down 10. Unless you have seriously jacked the spring pressure upon your valves or are running a new cam that doesn't have many miles on it the added zinc isn't going to make much difference, and those old engines prefer straight weight oil or that has been my experience.
I use Valvoline VR-1 straight 30w. Last time I checked the ZDDP content was 1400ppm, should be plenty for a stock engine ('54 powerglide 235) that rarely sees much over 3000 rpm. I used to wait until it went on sale at O'Reilly's but now I just buy it online from Amazon - pretty cheap too.
I worked in a gas station in the sixties when there were thousands of those on the road. All we ever used for oil changes and top ups was 10W30. Unless the owner was a cheapskate and the engine was an oil burner, then they bought straight 30 weight. If it is stock the valve train is low stress and today's zinc free 10W30 should be ok. But if you are nervous you could use Rotella or some other brand that still has zinc. Diesel engine oil still had zinc the last I heard.
Ok it seems now that I've been overdoin the viscosity in my engines, I guess it's time to go from 20w50 to 10w40 or 10w30 and of course still mineral . We can't use straight 30 here in Scandinavia because of the four seasons...
LOL we got 4 seasons here of course it only gets below zero for a month or so. Some of us have been using summer and winter oil for so long that we don't know any other way. You can't buy anything here but dead dinosaurs any more so mineral oil it is. There was a time that you could get vegetable based oil but those days are long gone. Synthetic has become popular in the last decade or two, I don't use it my engines are all from a different era. I figure if I still eat beans and cornbread instead of health food my engines can still use mineral oil instead of synthetic. We are both from the same era.
I use 15/40 rotella because it`s cheap and in cal. has the most zinc content. Don`t knock synthetics. At the races, a synthetic takes 3 times as long to clean up as a petroleum based oil when someone unloads the bottom of their motor. I have had that experiance
I've changed my mind after some research. Clifford performance, Patricks antiques and Tom Langdon's says that this kind of oil is the best way to go with in my old inline sixies Can't buy this in Sweden so I'm ordering from the US.