Zinc Rich Oil for Flat Tappet Cams

So far have been using 30 weight straight oil from valvoline vr-1. I wonder if to go for a different weight? One that's easier to find? Would 10/30 weight be an equal to 30? Or a little thicker say 10/40?

10w-30 is the somewhat the same as sae 30 in that they both have the same heat protection, however the sae 30 weight isnt a multi viscosity oil, the 10w-30 will act as a 10 weight in cold temps and a 30 weight in hotter temps. So if you see any temps colder than say 40 degrees the 10w-30 may be a better choice (Temps in regard to outside temp not engine temp).

Using thinner oil when its cold out takes stress off the oil pump and aids in quicker delivery of the oil in cold temps, using a multi viscosity weight oil gets you the best of both worlds. Plain sae 30 weight isnt reccomended for temps any lower than about 35-40 degrees depending on which chart you go by but the 10w-30 because of the multi viscosity 10 weight cold rating it should be good in temps as cold as 15-20 degrees.

Always remember in multi weight viscosity oils the w in 10w-30 or any other multi viscosity weight stands for winter because it is the cold viscosity rating, the number after is the hot viscosity rating

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I know this is published by gm but there are so many charts out there that all differ 5-10 degrees on the oil rating, this one looked closest to what i prefer as far as oil weights in the temperature ranges. Also if you have a vehicle with a owners manual there should also be a similar chart in it as well

Fwiw im running 15w-50 mobil one and she has no problem starting at 25-30 degrees.