Engine oil

[hanger]

So I’ve been using Valvoline 10-30 conventional in my 87 GW 360 since I bought it 5 years ago and now am unable to find it. What kind of oil are you guys using. I can’t seem to find anything but synthetic. I had read somewhere synthetic is bad for these old engines. I appreciate anyone’s experience and input on this.

[letank]

Castrol have the 10w30 conventional or part synthetic, or in 10W40 which is what I use. I tried the rotella 15W40 conventional. You can get all these by the gallon or even in 5 quart jug at wally world for a better price if your local parts store is out of it.
I used mobil 1 after a full gasket replacement once... but that old engine was burning a bit too much on short trips, no dripping just a loose engine.

[will e]

I use Valvoline VR1. It has a high zinc content. I order it via Amazon.