Engine oil weight question

[RPM - Robert]

I'll probably change my oil before winter using my normal Valvoline VR1 20W-50 but with the cold temps comming I'll exchange 1 quart with VR1 10w-30 which should net me a 17.5w-45 for winter 

I also got some Rislone zinc additive recently so I've put some of that in the crank case to bump up the zinc content.

The non synthetic VR1 already has zinc additive in it, there is no need to add more. We have been running the VR1 since the mid 90s in these things. We also run it in the 440 CI solid lifter LS in the Miata.

[86FJNJ]

Thanks Robert/Pat, I did some reading on it and saw somewhere that the Zinc content of the VR1 oil was around 1100 to 1400ppm but that the oils from back in the day actually had a bit more zinc content...but who knows if that's true, internet warriors can't be trusted.

I put the additive amount shown on directions and no issues with clutch slipping so far but will report back if I do experience any issues. Worse case is if I don't continue to use it in the FJ I'll throw it in the lawnmower and my generator during those oil changes.